Sarah moves from Manchester to Valencia in April. She starts a new job here and keeps a small pension from a former employer in the UK private sector. What can come as a surprise the following spring is that Spain is interested in her income from January, not just from April.
Spain does not split the tax year. Under the ordinary rules you are either resident for the whole calendar year or not at all, and a resident pays Spanish tax on income from anywhere in the world. If Sarah turns out to be resident for the year she arrives, her UK salary from January to March is part of the picture too. A double tax treaty may then change how some of that income is taxed, but that is a second step, taken item by item.
When Spain starts counting
Spain treats you as resident for a calendar year if you spend more than 183 days here, or if the main centre of your economic activities or interests is here. Sporadic absences abroad still count as days in Spain unless you can prove that you are tax resident in another country, which usually means a certificate from that country’s tax authority. And if, on the same tests, your spouse (not legally separated) and your dependent minor children live here, you are presumed to be resident too, unless you prove otherwise.
In practice, someone who arrives in March and stays will usually be resident that year. Someone who arrives in November usually will not, unless the family presumption or their economic interests make them resident anyway; otherwise residence normally starts the following year.
The UK, the US and Canada have their own residence rules, so it is quite possible to be resident in two countries for the same year. The tax treaty between Spain and your home country then has rules that decide where you count as resident for the purposes of the treaty, and which country may tax each kind of income; the wording differs from one treaty to another. US citizens have an extra layer, because the US taxes its citizens wherever they live: a US citizen resident in Spain normally files in both countries.
What to sort out first
Being resident does not always mean you have to file, but some people must file whatever their income, including anyone who claims a credit for tax paid abroad and anyone registered with Spanish Social Security as self-employed at any point in the year.
Most foreign income goes into the Spanish return. Where the treaty also allows the other country to tax it, the tax paid there is credited, up to the Spanish tax on that same income and only with proof that it was paid. Some income, though, can be taxed by only one country. Under the Spain–UK treaty, Sarah’s private-sector pension is taxed only in Spain. A pension paid by the UK government or a UK local authority for service to it, whether directly or out of a fund, is taxed only in the UK, with an exception for pensioners who are Spanish nationals resident in Spain. Where it is taxed only in the UK, Spain does not tax it, but may take it into account when setting the rate on the rest of the income.
Two things are worth checking early. Residents with accounts, investments or property abroad may have to file Modelo 720, an information return on assets abroad, separate from the income tax return, and crypto-assets held abroad with a provider that keeps the keys for you may have to be reported on another one, Modelo 721. And people who move to Spain to work may be able to choose a special regime, often called the Beckham Law, which has to be elected within six months of the start date of the job or activity, not of the day they arrive. It is worth comparing with real figures while the move is being planned.
It also helps to keep, from the start, proof of your arrival date and of your days in and out of Spain, your NIE (the foreigner’s identification number used for tax), statements from every country for the whole year and evidence of any tax paid abroad.
Sources: Personal Income Tax Act (Law 35/2006), articles 2, 9, 12, 80, 93 and 96; Income Tax Regulations, articles 61 and 116; General Tax Act, eighteenth additional provision; Order HFP/886/2023 of 26 July; Spain–UK double taxation convention, articles 17, 18 and 22.
By José Vicente Díaz Madrid, tax and accounting adviser, Grupo Avanza Consultores (Paterna, Valencia). General information on Spanish tax law as at October 2026; it is not personalised tax advice.