What's changed
Foreign residents who hold crypto or keep accounts outside Portugal are discovering, some later than they'd like, that this year's Modelo 3 tax return asks a lot more of them than in previous campaigns. The reporting window closed on 30 June, but the balance-due deadline — 31 August 2026 — is now the pressure point, and for expats with crypto wallets or offshore accounts, getting the underlying declaration right matters as much as paying on time.
The trigger is the operational rollout of the EU's DAC8 directive, which requires crypto platforms — including foreign ones operating in Portugal — to automatically report transaction data to the tax authority. 2026 is the year this obligation gains real operational force, with the transposition of the European DAC8 directive, obliging platforms — including foreign ones operating in Portugal — to automatically report transaction data. That data-sharing infrastructure gives Finanças, for the first time, a systematic cross-check against what taxpayers actually declare.
The forms that now matter
Anyone who sold, received as payment, or mined crypto assets during 2025 has concrete obligations on this year's return, and ignoring them isn't free. Anyone who sold crypto assets in 2025, received payments in that form, or mined them has concrete obligations to fulfil on the Modelo 3 IRS return, and ignoring them can be costly.
Where things get genuinely complicated for foreigners is Anexo J — the annex for foreign-source income. Crypto-asset income sourced abroad in 2025 must obligatorily be reported in Anexo J, to ensure correct tax compliance and avoid penalties. The catch many people miss: it isn't about where your wallet sits or whether a protocol is decentralised. Anexo J is frequently overlooked by crypto investors in Portugal, not because it's technically complex, but because many taxpayers don't understand that the tax residency of the platform or counterparty determines whether income counts as foreign-source. Use a non-Portuguese exchange and the income can be classed as foreign, triggering Anexo J regardless of your own residency status.
Short-term gains (assets held under 365 days) go on Anexo G; long-term holdings (over 365 days) — which are tax-exempt — still have to be reported on Anexo G1. Whenever the counterparty to a transaction is resident outside Portugal, the EU, the EEA, or a country with a double-tax treaty, taxpayers must fill in this specific disclosure field. That's the "new mandatory field" catching people off guard this year: it's not optional box-ticking, it's a hard requirement tied to where your trading counterparty is based — which matters directly for anyone routing transactions through exchanges based in jurisdictions with lighter tax regimes.
Frequent or professional trading activity is treated differently again, falling under Category B business income and Anexo B, and — same as capital gains — any income obtained through foreign entities under Anexo C also requires Anexo J to be completed and submitted.
The August 31 deadline
This is where the calendar gets unforgiving. Declarations were due between April and June, but if your tax assessment results in tax owed, you also have until 31 August 2026 to make the payment. Miss it, and interest starts accruing — the current late-payment rate applied to state debts, including IRS, is 7.221%, per Notice No. 18/2026/2 of 2 January 2026, down from 8.309% in 2025.
There is some flexibility. Amounts above €250 can be paid in instalments, provided you request that option through the Portal das Finanças before the deadline, and formally, the request window runs to 15 days after the end of the voluntary payment period (31 August). Plans of up to 12 instalments on debts up to €5,000 typically don't require a guarantee, though longer plans do.
Why this bites expats specifically
For foreigners who came to Portugal with existing crypto portfolios, offshore brokerage accounts, or savings left in a home-country bank, the practical risk isn't the tax rate itself — Portugal's 28% short-term / exempt long-term crypto treatment hasn't changed. It's the paperwork mismatch: DAC8 data now lets Finanças see transactions that taxpayers might once have assumed were invisible, and a return that skips Anexo J because "the wallet is self-custodied" or "the platform isn't Portuguese" is exactly the kind of gap the new automatic reporting is designed to catch.
What to watch next
Expect enforcement, not just forms, to tighten further. From 1 January 2026 Portugal began receiving crypto transaction data under the international CARF/DAC8 reporting framework, which means retroactive scrutiny of 2025 declarations is realistic, not theoretical. Anyone unsure whether their crypto or offshore holdings trigger Anexo J, or facing a balance due they can't cover by 31 August, should get advice before the deadline rather than after — our tax and NIF hub has more detail on how residency and reporting obligations interact. This is general information, not a substitute for guidance from Finanças or a qualified Portuguese tax adviser on your specific situation.
Sources