AT just asked me about €95 I earned in Sweden. In 2022.

A few months ago I got an email from the Autoridade Tributária. They wanted to know about income I earned in Sweden and Germany in 2022.

Not just my salary. They knew about €95.30 in bank interest from Sweden. And €106.17 from a German bank account. Four years after the fact, AT had exact figures for income I earned in countries I no longer live in, from bank accounts I barely remember having.

The email was polite but firm. It listed every amount, sorted by country and income category. It gave me 15 days to either file a corrected IRS declaration or explain why I hadn't included these amounts in the first place.

Here's the thing: I was right not to declare them.

The income was from before I moved to Portugal

In 2022 I was still transitioning between countries. The Swedish salary was from my own company there. I was a solo entrepreneur in Sweden too, running a limited company. The bank interest was from accounts I held while living in those countries.

When you become a tax resident in Portugal, you declare your worldwide income from that point forward. Income earned before your tax residency started belongs to the country where you were living at the time. My accountant confirmed this. I didn't include these amounts in my Portuguese IRS on purpose.

But AT didn't know that. All they saw was: Sweden and Germany reported income for this NIF holder, and it doesn't appear in his Anexo J.

EU countries share your financial data automatically

This happens through something called the Common Reporting Standard (CRS) and the EU's Directive on Administrative Cooperation (DAC). Banks and financial institutions in EU countries report account balances and income to their local tax authority. That information then gets shared with the tax authority of the country where the account holder is a tax resident.

It's automatic. You don't need to be under investigation. You don't need to have done anything suspicious. If you have a bank account in Germany and you're a Portuguese tax resident, the German tax authority will tell AT about the interest you earned. Every year.

The system covers employment income, dividends, interest, and other financial income. It covers essentially everything that passes through a regulated financial institution.

Why did it take 4 years?

Good question. I don't have a definitive answer. Maybe the Swedish tax authority was slow to share the data. Maybe AT only recently started cross-referencing older records against these reports. Maybe they sent the same email to thousands of people at once as part of a broader review, which is what it felt like, given the generic tone.

Whatever the reason, the takeaway is clear: silence doesn't mean they missed it. AT can come asking years after you filed.

The scramble for proof

Here's where it got painful. AT wanted documentation. Not just an explanation. They wanted proof that this income was earned before my Portuguese tax residency started.

Finding the Swedish documents was manageable. I still have contacts there, and Swedish systems are reasonably digital.

Germany was a different story. I left Germany in 2022. Finding bank statements from a German account, four years after closing it and moving to another country, required digging through moving boxes I hadn't opened since the move. Old paper statements, in German, from a bank I no longer have a relationship with.

I'm still not sure what I would have done if those papers had been lost. Flying back to Munich to request physical copies from a German bank, navigating their privacy procedures as a non-resident former customer. That's not a hypothetical nightmare, it was almost my reality.

The case is still pending with AT as I write this. I'm fairly confident the documentation I provided is sufficient. But "fairly confident" and "resolved" are not the same thing, and the uncertainty has been hanging over me for months.

What this means for you

If you're a trabalhador independente in Portugal earning any income abroad, here's what I learned:

AT knows about your foreign income. Not because someone reported you. Because EU financial institutions report it automatically. Every bank account, every dividend payment, every interest accrual. They share the data whether you owe tax on it or not.

Small amounts are not ignored. They flagged me for €95.30. Ninety-five euros and thirty cents. There is no minimum threshold below which AT doesn't care.

You need proof even for income you correctly don't declare. This is the part most people don't think about. If you have foreign income that shouldn't go in your IRS (because it's pre-residency, because it's already taxed under a treaty, because it falls under an exemption), you still need to be able to prove why you excluded it. Years later.

Keep documents for at least 4 years. Realistically, longer. The legal obligation is 4 years from the end of the tax year. But if AT can come asking in year 4, and your case takes months to resolve, you need those documents to survive well beyond that window. I'd keep everything for 6 years minimum.

Digital copies beat paper in boxes. If I had scanned those German bank statements when I received them, I would have saved myself hours of digging and genuine anxiety. Store your proof digitally, organized by tax year, the moment you get it. Don't wait.

What to keep and for how long

For each tax year, hold onto:

• Foreign bank statements showing interest earned
• Dividend statements from foreign brokers or banks
• Employment contracts and payslips from foreign employers
• Platform earnings reports (if you use Upwork, Toptal, or similar)
• Proof of tax residency dates (registration certificates, rental contracts, utility bills from each country)
• Tax returns filed in other countries for the same period
• Any documentation of tax paid abroad (you'll need this for double taxation relief on Anexo J)

Keep all of it for at least 6 years after the tax year ends. Keep it digital. Keep it somewhere you can find it at 2am when AT sends you an email with a 15-day deadline.

This is part of why we built the IRS reader tool. You upload your IRS declaration and supporting documents together, organized by tax year, so that when AT comes asking about €95 from four years ago, you're not tearing through moving boxes. The one thing worse than getting that email is getting it and not being able to find the paperwork.