You sold Bitcoin at a profit and left it off your return. Or you hold more than €50,000 on foreign exchanges and never filed Modelo 721. The Spanish tax agency knows, and with DAC8 arriving in 2026 it is going to know a great deal better.
Penalties can dwarf the tax you would have paid in the first place. But if you act before a formal demand lands, you can cut them dramatically.
The short version
| Situation | What can happen to you |
|---|---|
| You leave crypto gains off your tax return | Penalty of 50% to 150% of what you owed |
| You file late of your own accord | Surcharge of 1% to 15% (no penalty) |
| You do not file Modelo 721 | €300 per item (minimum €300) |
| You file the 721 with errors | €150 per incorrect item |
| You evade more than €120,000 | Prison sentence of 1 to 5 years |
Penalties for undeclared gains on your tax return
If you sell, swap or exchange crypto at a profit and leave it out of your tax return, the Spanish tax agency can penalise you. How severely depends on the amount and on whether there was any attempt to hide it.
Minor infringement
- When it applies: the undeclared amount is below €3,000 and nothing was concealed
- Penalty: 50% of the unpaid tax
A practical example: you made €2,000 selling Bitcoin. You should have paid €380 on your return (19%). The penalty is €190. Total paid: €380 + €190 = €570.
Serious infringement
- When it applies: the amount exceeds €3,000 or there was deliberate concealment (leaving it off the return on purpose)
- Penalty: 50% to 100% of the unpaid tax
A practical example: you made €20,000 selling ETH and did not declare it. Approximate tax due: €4,000. Penalty: between €2,000 and €4,000. Total: between €6,000 and €8,000.
Very serious infringement
- When it applies: fraudulent means were used (front men, third-party accounts, false invoices)
- Penalty: 100% to 150% of the unpaid tax
A practical example: you made €50,000 and used relatives’ wallets to hide it. Tax due: ~€10,000. Penalty: between €10,000 and €15,000. Total: between €20,000 and €25,000.
The penalty is always added to the tax you should have paid. It does not replace it.
What if I have no gains? What about losses?
If all you had during the year were losses on your crypto, there is no tax to pay. No real financial penalty either.
But declaring your losses is in your interest: you can offset them against gains over the next 4 years. If you lose €5,000 this year and make €5,000 next year, that €5,000 gain is tax-free provided you declared the losses in time.
If you file late with losses (tax due €0), the worst that can happen is a formal penalty of €100 for late filing. In practice the Spanish tax agency rarely applies it when there is no money to collect.
Surcharges for filing late (voluntarily)
If you missed the deadline but file of your own accord before a formal demand arrives, there is no penalty. Only a surcharge on the tax you owed:
| Delay | Surcharge |
|---|---|
| 1 month | 1% |
| 2 months | 2% |
| 3 months | 3% |
| 6 months | 6% |
| 12 months | 12% |
| More than 12 months | 15% + late-payment interest |
The surcharge is 1% for each full month of delay, up to a maximum of 15% (article 27 of the Spanish General Tax Act).
Key point: if the tax due is €0 (because you have losses), the surcharge is X% of €0 = €0. You pay nothing.
Example: you owed €1,000 on your tax return and file it three months late of your own accord. Surcharge: €30. Total: €1,030. Far better than waiting to be penalised (minimum penalty: €500).
Filing late of your own accord always beats waiting. The surcharge is far smaller than the penalty.
Modelo 721 penalties
Modelo 721 is the informational return for crypto held on foreign exchanges (Binance, Kraken, Coinbase and the like). It is compulsory if your balances at 31 December exceed €50,000.
The penalty regime as it stands
The Modelo 721 penalty regime follows the general LGT rules for informational returns (articles 198–199), after the CJEU ruling of January 2022 struck down the disproportionate penalties attached to Modelo 720 (assets held abroad).
| Breach | Penalty |
|---|---|
| Not filing the form | €300 per omitted item |
| Filing with incorrect data | €150 per incorrect item |
| Filing late of your own accord | €100 per item (min. €300) |
Each cryptocurrency on each exchange counts as one “item”. If you hold BTC, ETH and USDT on Binance and Kraken, that is 6 items.
Filing window
From 1 January to 31 March of the following year. If you miss it, file as soon as you can of your own accord to keep the penalty to a minimum.
Tax fraud: when prison comes into play
Where the amount evaded exceeds €120,000 in a single tax year, the Spanish tax agency can refer the case to the criminal courts.
| Offence | Sentence |
|---|---|
| Tax fraud (>€120,000) | 1 to 5 years in prison |
| Aggravated tax fraud (>€600,000) | 2 to 6 years in prison |
| Additional fine | Up to 6 times the amount evaded |
Below €120,000, the consequences are financial. There is no prison.
How does the Spanish tax agency know I hold crypto?
Right now (2026)
- Spanish exchanges (Bit2Me, Criptan): they report every one of your transactions directly to the AEAT
- Modelo 721: the data you reported yourself
- Bank cross-checks: the tax agency sees the transfers between your bank and the exchanges
- Blockchain analytics: tools such as Chainalysis that trace on-chain transactions
- International agreements: Binance and other exchanges already report data to several countries
From 2027 (DAC8)
The European DAC8 directive came into force in January 2026. That means:
- 2026: exchanges start collecting data on every European user
- 2027: they send that data automatically to the Spanish tax agency
- 2027–2028: the tax agency automatically cross-references what the exchanges report against what you declared
This reaches even non-EU exchanges with European customers. The days of opacity are over.
If you have not declared in earlier years, 2026 is your last window to put things right voluntarily before DAC8 puts everything on the tax agency’s desk.
Before you file anything, read through the full process for putting undeclared crypto right.
Time limits: when can they no longer penalise me?
| Type of liability | Time limit |
|---|---|
| Income tax (tax debt) | 4 years |
| Modelo 721 (penalty) | 4 years |
| Tax fraud | 5 years |
| Aggravated tax fraud | 10 years |
The clock starts at the end of the voluntary filing period. But any action by the tax agency (a letter, a formal demand, an audit) interrupts the limitation period and the clock resets to zero.
With DAC8, automatic data matching can generate formal demands that interrupt those limits. Do not count on the clock running out by itself.
How to put your situation right
Option 1: an amended return (the best option)
If you did not declare your crypto in earlier years, you can file an amended return that adds only the crypto part, leaving the rest of the return untouched (salary, rental income and so on).
Advantages:
- You pay only a surcharge (1%–15%) instead of a penalty (50%–150%)
- You avoid the penalty procedure altogether
- If you had losses, the surcharge is €0 and you also register them for future offsetting
- You can regularise only the crypto part without changing anything else
What you need:
- A profit-and-loss report for each year you want to regularise (using FIFO and covering all your exchanges)
- To file the amended return before a formal demand reaches you
Option 2: regularising after a formal demand
If the tax agency sends you a letter or a formal demand:
- The voluntary surcharge is no longer available to you
- You can accept the agency’s assessment with a reduced penalty
- Worse than acting voluntarily, but better than litigating
Option 3: an audit (the worst position)
If the tax agency opens a formal audit:
- Full penalty (50%–150%) plus late-payment interest
- No reductions for voluntary regularisation
- If the amount exceeds €120,000, criminal proceedings become possible
The sooner you act, the less you pay. The gap between regularising voluntarily and waiting for an audit can be 500%.
Specific cases: what do I do if…?
I only have losses and did not declare them
File the amended return. The surcharge will be €0 and you register the losses for future offsetting (up to 4 years). It is all upside.
I made very little (under €1,000)
Declare it anyway. There is no tax-free threshold for capital gains. The cost of not doing so (a 50% penalty) comfortably exceeds the tax you would have paid.
I hold crypto but have sold nothing
There is nothing to declare on your tax return. Simply buying and holding creates neither a capital gain nor a capital loss.
But if your balances on foreign exchanges exceed €50,000 at 31 December, you do have to file Modelo 721.
I did not declare in 2023 and 2024
You can file amended returns for both years. They are separate pieces of work: you need the P&L report for each year plus the amended return for each tax year. The limitation period for the 2023 tax year runs out in June 2028, so there is still time.
A letter from the tax agency has arrived
Do not ignore it. You have a deadline to reply (usually 10–15 working days). Gather all your paperwork and get in touch with a professional as soon as you can. Regularising in time reduces the penalty significantly.
Summary
| Situation | Consequence | Your best move |
|---|---|---|
| You did not declare gains | Penalty of 50%–150% of the tax | Voluntary amended return (surcharge 1%–15%) |
| You did not declare losses | Formal penalty of €100 (rarely applied) | Amended return (surcharge €0 + losses registered) |
| You did not file the 721 | €300 per omitted item | File it late |
| More than €120,000 evaded | Prison sentence | Urgent regularisation with an adviser |
| DAC8 (from 2027) | The tax agency will know everything automatically | Regularise in 2026 |
Need to put your crypto in order?
At Cryptoimpuestos we help you get square with the Spanish tax agency. We review your situation, calculate your gains and losses using FIFO, and file the amended returns so that you pay as little as the law allows.
If all you had were losses, regularising costs you next to nothing and lets you offset them in future.
Message us on WhatsApp and we will advise you with no strings attached.
Víctor Lázaro
Tax adviser, Cryptoimpuestos.es
