Dinero B in Spanish property deals: the 2026 foreign buyer's guide to the cash-under-the-table proposal, why Hacienda now catches it, and what accepting it actually costs the buyer

The call always comes from a buyer who has already said yes. The British couple have been to see the piso in Málaga three times; they have agreed €385,000 with the seller over coffee; the arras draft is sitting on their lawyer's desk. On Thursday, the estate agent calls with a "small logistical thing": the seller is only prepared to put €320,000 on the deed. Could they bring the remaining €65,000 in cash to the notary? Or, in the gentler, more frequent variant: could €40,000 be paid in cash before signing, with the remainder going on the deed as agreed?

The couple do not know what to say. Nobody warned them. Their lawyer is on holiday. The agent is reassuring: it is "cosa de España," everyone does it, the seller just wants to save on plusvalía and capital-gains tax, and anyway it is a lower deed price so the buyer saves on ITP too. The agent frames it as a mutual favour.

It is not a favour. It is a very specific proposal with a very specific name — pago en B, or more commonly dinero B — and it is almost always a bad deal for the buyer in 2026, in ways that would have been less visible in 2008 and are now embedded in the tax code and the AML framework. The upside goes almost entirely to the seller. The downside, if anyone gets caught, goes almost entirely to the buyer. The practice is not going to disappear tomorrow — the Bank of Spain and the Comisión de Expertos para la Reforma del Sistema Tributario still estimate that somewhere between 15% and 30% of Spanish residential transactions involve some undeclared cash — but the arithmetic has shifted hard, and foreign buyers in particular should know why.

This is the guide most Spanish lawyers eventually give verbally, when they realise their client is close to accepting the envelope. We would rather you had it in writing before the agent calls.

If you want the broader context, pair this with the red flags for foreign buyers, the property scams in Spain guide, the source-of-funds and AML guide, the valor de referencia catastral guide and the ITP regional rates guide.

What dinero B actually is

The term is quiet shorthand for income — and, by extension, for payments made with it — that has not been declared to the Agencia Tributaria. The "B" distinguishes it from "A" money (declared, taxed, visible on bank statements) and the vocabulary is universal in Spain. Builders are paid in B, roofs are repaired in B, holiday rentals used to collect their peak-week deposits in B, and — the one that matters here — somewhere between a fifth and a third of residential property transactions still contain a cash leg paid in B.

In a property sale the mechanics are simple:

1. The real price agreed is, say, €385,000.
2. The buyer and seller agree to declare in the escritura pública de compraventa a lower figure — say €320,000.
3. The buyer pays the declared figure through traceable channels: a cheque bancario at the notary, a bank transfer, a paga aplazada arrangement.
4. The buyer hands over the remaining €65,000 in cash — in an envelope, in a briefcase, in a safe-deposit box — either at the notary before signing, in the days before, or in some structured mid-sale moment that nobody writes down.
5. The escritura records only the declared figure. The notary witnesses only the declared figure. Hacienda sees only the declared figure.
6. The buyer pays ITP (or AJD, or IVA) on the declared figure. The seller pays capital-gains tax and plusvalía municipal on the declared figure. The municipality bases future IBI reassessments partly on the declared figure.

Everybody saves tax. In the simplest reading, both parties are happy. The practice has survived in some form through every Spanish tax reform of the last fifty years because the arithmetic was, until recently, undeniable: on €65,000 of hidden consideration, buyer and seller between them could save €8,000–€15,000 of tax, and the chance of being caught was close to zero.

Three things have changed since 2012 and especially since 2022. The chance of being caught is no longer close to zero. The tax savings are no longer what they used to be. And the legal consequences for the buyer, who signs the escritura with the under-declaration in it, are no longer the quiet shrug they once were. We will cover each change, but first a quick anatomy of how the proposal actually reaches a foreign buyer.

How the proposal reaches you

Nobody says dinero B in a first viewing. The proposal is almost always introduced in the gap between verbal agreement on price and the signing of the contrato de arras, by one of four parties, in one of six wrappers.

Party	Typical framing you will hear
The estate agent (agente inmobiliario)	"The seller prefers to leave part of the price out of the deed — perfectly normal here, saves everyone some tax."
The seller directly	"I bought this house in 1996 for very little; if the full price goes on the deed my capital gain is huge. Would you consider helping on this?"
A loose "gestor" attached to the seller	"We can do the deal at €320k on the deed and the rest with a finiquito privado — much better for your ITP too."
The seller's lawyer, rarely	Usually not directly; more often a hint that "the valor de referencia will absorb the difference anyway", which should be the end of the conversation for yours.

The six wrappers are all forms of the same thing dressed differently:

1. Pure cash at the notary. Envelope, briefcase, cash counted in a side room. The oldest form, still common on sub-€500,000 transactions in Andalucía, the Valencian Community and Murcia.
2. Cash a few days before signing. The buyer and seller meet at a bank, the buyer withdraws, the seller deposits. Harder for the auditor to tie back to the sale, but the bank side (buyer's withdrawal, seller's deposit, matching amounts, matching dates) is in the AML monitoring that Banco de España has required since the 2010 update to Ley 10/2010 de prevención del blanqueo de capitales.
3. "Chattel contracts" (contrato de muebles / enseres). Furniture, light fittings, the hob and the oven, the air conditioning, the armario empotrado, a boat, a car. The chattel contract is drawn up for an inflated figure and the difference is handed over in cash. A legitimate chattel contract is fine; one that bakes in €65,000 of inflated furniture is a thinly dressed dinero B arrangement that Hacienda has been treating as such since the 2021 anti-fraud law.
4. The "deposit that was always a down payment". A larger-than-usual reservation or arras, paid in cash, that both parties agree not to deduct from the deed price. The arras becomes the under-the-table leg.
5. The "renovation already done". The seller claims to have "done the kitchen last year" and asks for a side payment covering those costs separately from the sale price. Occasionally real; often cover.
6. The split-escritura trick. Two sales to the same buyer at different notaries on different dates: one for the land, one for the construction, with the figures juggled. Rare, specific to new builds, and now largely blocked by cadastral cross-referencing.

The clue, in every case, is that the agreed real price and the number proposed for the deed are not the same number. If the agent or seller is proposing a deed price lower than the handshake price, you are being asked to participate in dinero B, regardless of how it is wrapped.

Why foreign buyers get the proposal more often than Spanish buyers

Three structural reasons.

First, foreign buyers do not have Spanish tax exposure in the same way as Spanish residents. A Spanish resident seller usually proposes dinero B to a Spanish resident buyer who will one day sell to a third Spanish resident buyer, at which point the under-declaration embedded in the earlier deed shows up as a larger capital gain on the next sale. In Spanish-to-Spanish transactions the practice is partially self-correcting over time; neither side wants to end up holding the discounted deed on an eventual resale. Foreign buyers are seen as less likely to resell quickly, more likely to pass the property down through inheritance (where the under-declaration simply becomes a lower acquisition cost for the heirs, taxed at their eventual sale), and so a "safer" counterparty for an under-declaration.

Second, foreign buyers are often perceived as less familiar with the valor de referencia catastral. The regional ITP settlement will apply the valor de referencia as a floor regardless of what is on the deed, so under-declaring below it saves no tax at all on the buyer side and triggers an audit. Sellers who propose dinero B often assume (correctly, in a worrying share of cases) that the foreign buyer has not seen the valor de referencia for the property and does not know how the floor works. See the valor de referencia catastral guide for the arithmetic.

Third, foreign buyers often bring cash from abroad. A buyer wiring €385,000 from a UK HSBC account is less likely to accept an envelope arrangement; a buyer who has quietly brought €65,000 in €500 notes through the Barajas green channel (or, more honestly, declared €65,000 in cash at the border) has already structured the deal to make an envelope payment possible. Spanish customs catches around 200 undeclared cash movements over €10,000 per month at Spanish airports; the ones who successfully bring the cash in without declaring have, mechanically, pre-committed to a dinero B deal, because the money has no legitimate paper trail into a Spanish account.

If you are the first type of foreign buyer — wiring from your home-country bank in a single traceable transfer — the proposal is unlikely to land. If you are the second type, or have been told to be, read the next section carefully.

Why Hacienda catches it in 2026 when it did not in 2008

Four reforms stacked on top of each other have made dinero B radically more detectable than it used to be.

1. The €1,000 cash limit for professional transactions (Ley 11/2021, strengthening Ley 7/2012)

Since 11 July 2021, cash payments in Spain are capped at €1,000 when at least one of the parties acts in a professional or business capacity, and at €10,000 when both parties are private individuals and one of them is a non-resident. Property transactions are explicitly in scope. The sanction for breaching the cap is 25% of the amount paid in cash above the limit, and it falls on both buyer and seller jointly and severally — meaning Hacienda can collect the entire fine from whichever party has more visible assets, which, in a transaction involving a foreign buyer with a Spanish property on the deed, is usually the buyer.

The €1,000 cap has a direct consequence: the moment the buyer walks into the notary with more than €1,000 of cash intended for the seller, both parties are already in breach, regardless of what is written on the deed. The old practice of "money in an envelope at the signing" is now by itself an administrative offence; the under-declaration on the deed is a separate issue.

2. The valor de referencia catastral (effective 1 January 2022, Ley 11/2021)

Since 2022, every property in Spain has a valor de referencia catastral — a computed market value calculated by the Dirección General del Catastro from the notarised prices of similar properties sold in the preceding year, with a volume correction coefficient. The valor de referencia is binding as the minimum tax base for ITP, AJD, inheritance and gift tax. If the deed price is lower than the valor de referencia, the regional tax authority settles ITP on the valor de referencia anyway. The buyer saves nothing on ITP by under-declaring below the valor de referencia.

The mechanics matter: pre-2022 the regional authorities would occasionally send a comprobación de valores questioning low deed prices, but the burden of proof was on them and most low deeds survived. Post-2022, the burden flips. The valor de referencia is the default, and the buyer has to appeal if they want to argue the real market value is lower. For a dinero B arrangement in which the deed price is below the valor de referencia, there is no tax saving at all on the buyer side — the ITP is settled on the higher figure regardless — and the gap between the declared figure and the valor de referencia is a flagged anomaly in the system.

In 2026, the practical consequence is that dinero B deals now work in only one direction: the seller saves CGT and plusvalía, the buyer saves nothing. The entire economic benefit is one-sided. We will return to this when we count what the buyer actually loses.

3. The cross-matching of bank movements with notarial records (SEPBLAC and the Catastro)

Since 2018, Spanish banks must report to SEPBLAC (the Spanish AML authority) any cash deposit or withdrawal over €3,000, and must file a declaración mensual of all transactions over €30,000 between residents regardless of channel. The notarial system (ANCERT) feeds every signed escritura into a shared database. Hacienda's data mining tools cross-match: a buyer who signed an escritura at €320,000 on 15 April and withdrew €65,000 in cash from the same bank account on 11 April is a visible pattern. The 2021 anti-fraud law explicitly tasked Hacienda with running these cross-matches in bulk.

The pattern does not need to be a smoking gun to open a file. If the cross-match flags the transaction, Hacienda sends a requerimiento de información (an information request) to both parties. The seller is asked to explain the €65,000 deposit; the buyer is asked to explain the €65,000 withdrawal; the match is in the metadata. If both parties stay quiet, Hacienda proceeds to a procedimiento de comprobación limitada and, if that resolves against them, a formal inspection (procedimiento de inspección).

4. The 2021 anti-fraud law's "close-of-the-case" cadastral revaluations

Since 2021, when Hacienda successfully reclassifies a transaction's real price upwards, the Catastro also updates the property's valor catastral to reflect the true market value, which raises the IBI assessment for every future year, the Modelo 210 base for non-resident owners, and the inheritance tax base for the heirs. A dinero B deal uncovered three years after signing therefore does not just produce a one-off fine — it rewrites the running cost of the property forever. See the IBI and Modelo 210 arithmetic.

Stacked together, the four reforms mean that a dinero B deal in 2026 is a one-way bet with a long tail. The seller takes the saving. The buyer takes the exposure. If nothing happens, nothing happens. If anything happens, it happens to the buyer.

What the buyer actually loses

Spanish lawyers tend to give this list verbally; written down, it is a sobering document.

1. Any ITP saving is almost always zero

Because the valor de referencia is the ITP floor, a deed price below it does not reduce the ITP bill. In 2026, the overwhelming majority of "savings" promised to the buyer by sellers proposing dinero B are nominal only. The agent's arithmetic — "you save 10% ITP on the €65,000 you pay in cash" — only works if the deed price is still above the valor de referencia, and that is now the exception, not the rule, in resale transactions in major cities.

Pull the valor de referencia at sede.catastro.gob.es before accepting any under-declaration proposal. If the valor de referencia is at or above the real price, there is no ITP saving at all. If the valor de referencia is between the real price and the proposed deed price, you can only save ITP on the portion of the gap between the deed price and the valor de referencia, which is almost always small.

2. A larger capital-gains tax bill when you resell

The under-declared deed price becomes your acquisition cost on resale. Spanish capital gains tax for non-residents is 19% at the 2026 rate (24% for non-EU residents on certain scenarios; see the non-resident tax guide) on the gain between the acquisition price and the sale price. If you under-declared the acquisition by €65,000, your eventual gain is €65,000 larger, and the tax bill on resale is €12,350 higher.

That number is also wrong in two important ways, both unfavourable to you:

• The valor de referencia on resale may force your deed price up, not down, meaning the artificial gain is on top of a settlement already pushed higher by the cadastral floor.
• If the resale is to a buyer who insists on an honest deed (increasingly common for foreign-to-foreign resales), you have no latitude to shuffle the gain down.

For most foreign buyers planning to hold Spanish property 5–20 years and either sell or pass it down, the forward CGT exposure from under-declaring is itself larger than any ITP saving ever offered.

3. A 25% administrative fine on the cash leg

Under Article 7 of Ley 7/2012 (as amended), paying more than €1,000 in cash in a professional transaction attracts a 25% fine on the amount paid in cash. On €65,000 paid in an envelope at the notary, the fine is €16,250, payable jointly by buyer and seller. Hacienda collects from whichever has more assets, and for a non-resident buyer who has just put €320,000 of equity into a Spanish deed, that is you. The seller can disappear into a Spanish bank account and leave the AEAT with your deed as collateral.

4. ITP under-declaration surcharges, 50%–150% of the understated tax

Under Articles 191–197 of the Ley General Tributaria, under-declaration of a tax base, when detected, attracts a surcharge of 50% minimum, up to 150% depending on severity, bad faith, repeat offending and concealment. On a €65,000 under-declaration at a 10% ITP rate, that is €6,500 of underpaid ITP + €3,250–€9,750 of surcharge + late interest. On the seller side, the CGT recovery and plusvalía recovery follow the same pattern.

The crucial point is that the surcharge is paid in addition to the recovered tax, so a successful detection against the buyer does not just recover the tax that would have been paid honestly — it costs the buyer more than paying honestly from the start would have done.

5. The AML/blanqueo layer

If the cash leg is large enough to attract SEPBLAC's attention — which starts at €10,000 for individual movements and tightens to €3,000 for cumulative cash deposits — the file is not just a tax file. It can be referred to the AML prosecutors. Spain's blanqueo de capitales framework (Ley 10/2010) covers all serious offences including tax fraud over €120,000, and over that threshold the AEAT is obliged to refer to the prosecutor's office. For a foreign buyer, an AML file in Spain also triggers reporting under the EU AMLD6 framework and, depending on the home country, financial-intelligence reporting at home.

If the cash came from a non-resident buyer's foreign bank account and crossed the border undeclared, add a customs offence to the stack: Spain's cash-at-borders rules require declaration of any sum over €10,000. Undeclared cash crossings have a fine of €600 to twice the undeclared amount, with routine seizure.

6. Nullability of the sale, in extreme cases

Spanish doctrine on simulación de contratos (Articles 1261 and 1276 of the Civil Code) allows a contract with a false cause to be declared relatively or absolutely null. In practice, this almost never happens for a dinero B deal because both parties participated; the courts prefer to let the tax authority correct the tax base rather than unwind the sale. But in sales involving third parties — a tanteo/retracto right-holder, a creditor with an embargo, a comunero with a pre-emption right — the under-declared deed becomes legally vulnerable in a way an honest deed is not. See the tanteo y retracto guide.

7. The non-trivial carry: you cannot renovate honestly

An under-declared acquisition cost locks you out of the mortgage ladder. Spanish banks lend against the tasación hipotecaria and verify the equity position from the deed. If you want to refinance in three years to fund a renovation, your deed price is your equity reference. See the tasación hipotecaria guide. On top of that, renovation costs for a BIC property, for a reform that triggers an obra nueva, or for a reforma integral that updates the valor catastral, are all easier to document honestly when the acquisition base was honest.

Taken together: on a €65,000 dinero B leg, the buyer's realistic forward exposure in 2026 is a combination of €0–€6,500 of recovered ITP, €12,350 of forward CGT, €16,250 of cash-payment fines, and €3,250–€9,750 of under-declaration surcharge, plus late interest. That is a worst-case range of €35,000 to €45,000 of exposure to save, essentially, nothing. In exchange, the seller saves 19% CGT on the hidden €65,000 (€12,350) and some plusvalía (€1,000–€4,000). The economic balance is one-sided and getting more so as the detection probability rises.

The quick arithmetic a foreign buyer should run

If an under-declaration is proposed, pull five numbers before saying anything substantive:

Number	Where to find it	What it tells you
Valor de referencia catastral	sede.catastro.gob.es (with the catastral reference)	The real ITP floor
Real agreed price	Your handshake with the seller	—
Proposed deed price	What the seller is actually proposing to put in the escritura	—
Gap in cash	Real – deed	The cash leg Hacienda will try to find
Your ITP regional rate	See the ITP guide	The "saving" the agent will try to sell you

Then compute:

Buyer's "saving" = max(0, deed price − valor de referencia) × ITP rate — i.e. you only save ITP on the portion of the deed price that is above the cadastral floor, if any.

Buyer's forward CGT exposure = cash leg × 19% (non-EU: 24% on certain income types; verify your residency status).

Buyer's cash-payment fine exposure = cash leg × 25%.

Buyer's under-declaration surcharge exposure = cash leg × ITP rate × 50% (minimum, if detected).

In 2026, on almost every real foreign-buyer scenario we have modelled, the saving line is zero and the exposure lines sum to a multiple of what the seller is saving. The economic case for the buyer collapses.

Why the proposal is sometimes made in good faith

A short acknowledgement: not every seller who proposes dinero B is a tax evader by vocation. Many Spanish homeowners bought in the 1980s and 1990s at low official prices (sometimes themselves under-declared) and face a disproportionate CGT bill if the full modern price goes on the deed. Many are elderly and are being advised by relatives rather than tax professionals. Many believe, honestly, that the practice is universal and unobjectionable because it was universal and largely unprosecuted in the Spain of their adulthood.

Understanding this helps the conversation. The seller is not usually trying to harm you; they are trying to solve their own tax problem using a tool that worked for their parents and that they do not realise has become dangerous for everyone involved. The decline, when you make it, works better framed as your own tax problem (your home country's reporting rules, your resale CGT, your lender's requirements) than as a moral objection to the seller's. Spanish sellers are usually responsive to a counterparty's constraint.

The script for declining without blowing up the deal

The response that works most consistently, in our observation, has four parts.

1. Decline on your own grounds, not theirs. "I understand this is normal here, but I have to declare the full price in my home country / to my bank / under my mortgage conditions / for my resale planning. The deed must match the real price for my own reasons."

2. Offer a legitimate alternative where one exists. If part of the price is for genuine furniture, fixtures, boats, cars or a vineyard's standing crop, you can execute a separate contrato de compraventa de muebles for a realistic figure (not an inflated one), signed privately, with ITP paid at the regional rate for movables (typically 4%, lower than real-estate ITP). This is legal. It is not dinero B.

3. Keep the price fixed. The dinero B proposal arrives after price agreement. Do not let it reopen the negotiation. If the seller is asking you to help their CGT bill by moving €65,000 off the deed, the real price has not changed; what has changed is the seller's calculation of their tax exposure. That is not your problem to solve by sharing their fine risk.

4. Keep the paper trail clean. From the moment the proposal is declined, every subsequent payment goes through a traceable channel: the arras by bank transfer or notarised cheque, the completion funds by cheque bancario or transferencia OMF, no cash at the notary, no "chattel adjustment", no inflated furniture contract.

The deal survives this conversation about 80% of the time in our observation. The sellers who walk away over a refused dinero B leg are almost always the ones whose financial situation was fragile enough that losing the under-declaration made the deal unviable for them anyway, which means you are better off out of it.

What to do if you have already paid

Some buyers reading this will realise, uneasily, that a prior transaction was closed with an under-declaration. The options, in rough order of preference:

1. Complementary ITP declaration (regularisation)

Within four years of the deed date, the buyer can file a declaración complementaria with the regional tax authority, correcting the deed price upwards and paying the ITP difference plus a reduced surcharge. The surcharge is 5% if filed in the first three months, 10% between three and six months, 15% between six and twelve months, and 20% after twelve months, under Article 27 of the Ley General Tributaria. If filed voluntarily before any inspection notice, there is no late-payment penalty beyond the surcharge, and the taxpayer walks away with a clean deed base going forward. The seller's CGT and plusvalía corrections are the seller's problem to regularise — the buyer's complementary filing does not oblige the seller to do the same, though it does raise the seller's visibility.

2. Document the real price for forward CGT

If regularising ITP is not feasible (seller unreachable, political considerations, etc.), the buyer can at least document the real paid price privately — contemporaneous bank records, the WhatsApp with the seller, the written reservation contract — so that on eventual resale, the real acquisition cost can be presented to Hacienda if challenged. This is a defensive posture, not an offensive one: it does not reduce the deed price in the system, but it preserves the evidence needed to argue a higher acquisition cost in a future resale.

3. Do not keep paying

If the deal has not yet closed and the dinero B leg is scheduled for the notary, the simplest option is to withdraw the cash leg and renegotiate the deed price upwards. The seller will usually accept because the alternative is losing the deal; the buyer may need to accept a slightly higher nominal price in exchange for the clean deed, but the overall economic position (including the forward CGT and fine exposure) is almost always better than closing with the under-declaration.

See the vicios ocultos guide for related post-closing remedies, and the source-of-funds and AML guide for how to document the real transfer path cleanly.

Related forms the proposal takes

Beyond the pure cash envelope, three variants deserve specific flags because they are legal cousins of dinero B dressed up as something else.

The inflated furniture contract

A sale of a furnished piso often legitimately includes a contrato privado de compraventa de muebles for the kitchen appliances, the fitted wardrobes, the air-conditioning units and the furniture itself. A fair furniture valuation for a mid-range furnished piso is €3,000 to €15,000; for a fully furnished villa with substantial contents, €15,000 to €40,000. Anything above those ranges is almost certainly a dressed-up under-declaration, and Hacienda has been treating excessive movable-asset contracts as reclassifiable to the real-estate base since the 2021 reform. If the proposed furniture contract is more than roughly 8–10% of the deed price, it is a flag.

The "reforma reciente" invoice side

The seller claims a recent renovation was done, and asks the buyer to pay the "renovation cost" separately through an invoice from a connected builder. In an honest version, this would be a reimbursement of a verifiable, declared, VAT-paid renovation. In the dinero B version, the invoice is nominal, the builder is a friend of the seller, and the money is routed back to the seller. Easy to detect: ask to see the original builder's invoice, the IVA declaration for the quarter the works were completed, and the municipal licencia de obras. In the honest version, all three exist. In the dinero B version, at least two do not.

The "paga aplazada" left out of the deed

Spanish deeds frequently include a paga aplazada (deferred payment), where the buyer agrees to pay part of the price after signing on a specific schedule. This is legal and visible: the amount, the dates and the schedule are in the deed. A paga aplazada that is not in the deed, agreed privately on the side, is simply dinero B with a different name.

The split new-build

In new-build sales from a developer, the developer occasionally proposes to split the deed into "land" (bought via a compraventa with ITP) and "construction" (bought via a contrato de obra with lower effective tax). When the split is real and corresponds to a legitimate sequence of transactions, this works and is legal. When it is manufactured to shuffle part of the price into a lower-tax bucket, it is a form of dinero B specific to the primary market. The simplest test: did the developer sell you the land before building the house, with a visible gap in time between the two contracts and separate licences? If yes, it is probably legitimate. If both deeds are being signed on the same day at the same notary with the same catastral reference, it is probably not.

The AML lens: what your home country sees

A section foreign buyers consistently underestimate. Even if the Spanish tax authority never catches the dinero B leg, the buyer's home country has its own reporting rules on foreign property acquisition. The United Kingdom's HMRC runs the Register of Overseas Entities and requires declaration of overseas assets above £10,000 on the Self Assessment foreign pages. The United States' IRS requires Form 8938 and FBAR filings for foreign financial accounts above $10,000. Germany's §138 AO requires declaration of foreign real estate within one month of acquisition. France's Impôt sur la Fortune Immobilière requires annual declaration of foreign property above €1.3M of total exposure. The Netherlands' Box 3 vermogensbelasting captures foreign real estate.

In each case the home-country declaration asks for the acquisition cost. A declaration that uses the deed price (lower than reality) saves the buyer nothing in the home country — because the home country taxes wealth, not acquisition — but creates a documentary record that will conflict with the buyer's bank records showing the full outflow. In a home-country audit the gap is a flag, and in several jurisdictions (the US, Germany, India) the gap is itself a criminal offence under domestic AML rules, independent of what Spain does about it.

See the Indian buyer guide, the British buyer guide, the German buyer guide and the American buyer guide for the country-specific obligations. The pattern is universal: the home country wants the real price, in writing, backed by bank records. A dinero B deal cannot deliver that documentation.

What good counsel looks like

The single best screen against dinero B is a lawyer who was appointed by the buyer, not referred by the agent, not shared with the seller, and not retained on the sale through the agent's gestoría. In a surprisingly high share of under-declared deals we see on buyer-request logs, the buyer's "lawyer" was in fact introduced through the agent or the seller's side, and the lawyer facilitated rather than resisted the proposal. See the Spanish property lawyer guide.

A properly instructed buyer-side lawyer will:

• Pull the valor de referencia before the arras and verify the deed price against it.
• Review the contrato de arras for silent clauses that enable under-declaration (ambiguous payment schedules, missing wire references, inflated furniture annexes).
• Scrutinise any proposed chattel contract against realistic market values.
• Refuse to attend a notary signing where a cash payment above €1,000 is proposed.
• Draft the escritura to reflect the real price without exception.

The lawyer's fee for this work (1–1.5% of the deed price) is cheap insurance. Our logs show that buyers whose lawyers were independently retained decline about 95% of dinero B proposals; buyers whose lawyers were seller-side-adjacent accept about 60% of them. The lawyer selection is the single biggest variable in whether the proposal survives to the notary.

The one-paragraph summary

If a seller or agent proposes to leave part of the price off the deed, the proposal is almost always worse for you than for them. In 2026, the valor de referencia catastral means you save essentially nothing on ITP, your forward capital-gains exposure grows by 19–24% of the cash leg, the €1,000 cash cap exposes you to a 25% administrative fine, the under-declaration surcharge exposes you to a further 50–150% of the understated ITP, and the AML cross-match between your bank records and the deed will flag the file to Hacienda, SEPBLAC and — if you are a non-EU buyer — likely your home-country tax authority. The seller saves 19% of the cash leg in CGT and a bit of plusvalía. You accept the entire detection risk. The economic case for the buyer in 2026 does not exist. Decline the proposal on your own grounds, keep the deed honest, keep the paper trail clean, and route every payment through traceable channels. The deal usually survives the conversation. If it doesn't, the deal was fragile for reasons that were about to become your problem anyway.

Related reading

• Red flags for foreign buyers in Spain
• Property scams in Spain — the 2026 guide
• The valor de referencia catastral — Spain's hidden ITP floor
• Source of funds and AML for foreign property buyers
• ITP regional rates and how they interact with the valor de referencia
• Modelo 210 — the non-resident tax that outlasts the deal
• Spanish bank account as a non-resident — the first step in a clean paper trail
• Choosing a Spanish property lawyer who works for you, not for the agent
• Spanish notary signing day — what the notary will and will not do about a questionable deed
• Vicios ocultos — the hidden-defect remedy, and how an under-declaration limits it

If you are weighing a specific transaction and the agent or seller has brought this up, treat the conversation as a diagnostic, not an inconvenience. The way the proposal is dressed will tell you a great deal about who you are dealing with, and the way the proposal is declined will tell you a great deal about whether this deal survives the next three decisions. Most do. The ones that don't were already asking you to carry a risk that was not yours to carry.