Daniel Okafor lived in Lisbon for six years. While he was there he opened a deposit account with a Spanish bank, as a non-resident, and let it grow to 40,000 €. In 2025 he moved to Málaga. In spring 2026 he receives two letters almost at once: the Spanish bank asks him to "prove his tax residence" because his contact address is now Spanish, and his Portuguese bank sends him a form on which to declare where he is resident for tax purposes. Daniel assumes he has to obtain two official certificates, one in each country. In reality, he probably needs neither.
Why banks ask so many questions
Since the automatic exchange of information on financial accounts came in, institutions in most countries have had to identify their clients' tax residence and report the details of non-residents' accounts to their own administration, which passes them on to the administration of the country of residence. The international standard that governs this is known as the CRS, and US clients are also subject to a system of their own.
To comply, the bank does not in principle need an official certificate. What it needs is a self-certification: a form signed by the client declaring their country or countries of tax residence and their tax identification number in each. That is the letter Daniel received from Lisbon.
The official certificate comes into play when the bank has reason to doubt what you declare, or when a specific rule requires it in order to apply a different tax treatment.
When a declaration is enough and when the document is needed
| What the bank asks for | What for | What is usually enough |
|---|---|---|
| A residence self-certification form | To identify you for exchange of information purposes | Your signed declaration, with your tax number in each country |
| Clarification because your details do not fit (address, telephone, payment instructions) | To resolve conflicting indications in its file | Self-certification and, often, some supporting document |
| Treating you as non-resident at a Spanish institution | To apply the non-resident account treatment and, where relevant, exemptions | An official certificate from your country or the residence declaration on the approved form |
| Applying a treaty to the income | To withhold less | A certificate for treaty purposes |
The third row has an express legal basis in article 28 of the Regulations on tax management and inspection (Royal Decree 1065/2007). Its paragraph 7 excludes from the general identification regime the accounts of people who have proved that they are not resident in Spain. And its paragraph 9 says that this status may be proved to the institution by a certificate of tax residence issued by the tax authorities of the country of residence, or by a declaration of tax residence on the form approved by the Ministry.
What not updating his file costs Daniel
When Daniel lived in Portugal, his Spanish interest was exempt. Article 14.1.c) of the Non-Resident Income Tax Act (IRNR) exempts interest obtained by residents of another European Union State, and the bank withheld nothing from him.
Daniel is now resident in Spain. His interest is taxed under the IRPF (the Spanish personal income tax) as income from movable capital, and article 90 of the IRPF Regulations sets withholding at 19 %.
- Deposit balance: 40,000 €.
- Agreed annual return: 2.5 %.
- Interest for the year: 40,000 × 2.5 % = 1,000 €.
- Withholding if the bank treats him as a non-resident living in Portugal: 0 €.
- Withholding if it treats him as resident in Spain: 1,000 × 19 % = 190 €.
If Daniel does not reply and the bank goes on treating him as a Portuguese resident, it will withhold nothing. That does not mean he owes nothing: he will have to declare that interest in his Spanish income tax return, and his bank file will still say something that is no longer true. Moreover, the information on his account will travel to Portugal and not to Spain, which may prompt questions from both administrations.
The sensible course in his case is to tell the Spanish bank that he now lives in Spain, giving his NIE (the foreigner's identification number), and to give the Portuguese bank the same information. He does not need the Spanish residence certificate for either, unless one of the banks expressly asks for it.
When it does pay to have the certificate to hand
There are situations in which the official document saves arguments:
- Your foreign bank doubts your residence because you still have an address or telephone number in its country.
- You are tax resident in Spain but spend long periods abroad and your bank wants more than your word.
- You need a foreign bank to apply a treaty to the interest or dividends on your account.
- You are moving away from Spain and want the Spanish institution to stop treating you as resident.
In the first and second cases, if you live in Spain, the certificate is issued by the Agencia Tributaria, the Spanish tax agency; the ordinary version is usually enough because no treaty is being invoked. We explain this in the difference between the ordinary and the treaty certificate. In the third, the treaty version is needed. In the fourth, the certificate is the one from your new country, and you ask its administration for it yourself.
If your bank has sent you a letter and you are not sure exactly what it is asking for, you can forward it to us through the certificate form and we will tell you which document answers that request.
What you sign on that form is your statement of where you are tax resident, and the person who signs it answers for it. Declaring a residence you do not have in order to stop an account's details reaching an administration does not make the obligation to pay tax where it is due disappear. If your residence is doubtful, because two countries could claim you, resolve that first; we deal with it in who issues the certificate if two countries consider you resident.
The foreign account seen from Spain
Daniel keeps his account in Lisbon. As a Spanish resident, besides declaring the interest it generates, he has to assess whether its balance, together with that of other accounts abroad, obliges him to file Modelo 720, the Spanish return on assets held abroad, which uses code C for accounts and is generally triggered when that block exceeds 50,000 €. Exchange of information means the Agencia receives the details of that account from Portugal, so the prudent course is for what you declare to match what arrives. The guide to the three blocks of Modelo 720 explains how it is calculated.
A simple order of work
- Read exactly what the letter asks for: a self-certification, a clarification or an official certificate.
- If it is a self-certification, fill it in with your real residence and your identification numbers.
- If they ask for a certificate, find out whether the ordinary one is enough or the treaty one is needed.
- If you have to apply for it in Spain and have no electronic signature, there are alternatives, which we explain in how to apply without a digital certificate.
The Salama Tax page explains which certificate works for each recipient. A bank may accept a document or not according to its own procedures, and no answer given to it obliges the institution to treat you in any particular way.