Working as a Self-Employed Freelancer in Spain as a Foreigner: A Complete Guide to Registration and Obligations

Working for yourself in Spain as a foreigner is perfectly possible, and increasingly common among expats and digital nomads. What throws people off is not the difficulty, but the sheer number of acronyms and authorities involved. This guide walks you through, from scratch and in order, what you need to start invoicing legally as an autónomo, the Spanish term for a self-employed worker.

First things first: your NIE and the right to work

The first document you need is the NIE (Número de Identidad de Extranjero, or Foreigner Identification Number): a personal, unique and permanent number that identifies foreign nationals before the Spanish authorities. Without it you cannot start a business activity, sign significant contracts or file taxes. You can apply for it at National Police stations or immigration offices, or at Spanish consulates in your home country.

One important distinction: having an NIE does not mean you are allowed to work. European Union citizens can set up as self-employed without any further formalities. If you come from outside the EU, you need a residence permit that authorises you to work for yourself (there are, for example, specific visas for entrepreneurs and for international remote workers). Conditions change frequently, so check them with official sources or a professional before taking the step.

Registering on two fronts: the Tax Agency and Social Security

To operate legally you must register with two different bodies, and it pays not to confuse them.

1. The Tax Agency (AEAT, Agencia Estatal de Administración Tributaria). This is done through the census declaration, Modelo 036, where you state your activity, start date, tax address and the taxes you will be subject to. There is a simplified version, Modelo 037, designed for straightforward cases, although in practice almost everyone uses the 036. In this step you choose, among other things, whether you will apply VAT and withholding tax on your invoices.

2. Social Security. Self-employed workers pay contributions into the RETA (Régimen Especial de Trabajadores Autónomos, the Special Regime for Self-Employed Workers). These contributions entitle you to public healthcare, temporary incapacity benefits and your future pension. If you are a foreigner, also check whether your country has a Social Security agreement with Spain to coordinate contributions.

A practical point: to complete these procedures online you will need a digital certificate or the Cl@ve system, the electronic identification used by Spanish public administrations.

What you will pay: contributions based on income brackets

Since 2023 the monthly RETA contribution is no longer a flat amount: it depends on your net income (revenue minus deductible expenses). There is a table of brackets, and the higher your income, the higher your contribution. When you register, you estimate your income for the year and you can adjust your bracket during the year; once the year ends, Social Security compares your forecast with what you actually declared to the Tax Agency and settles the difference, in your favour or against you.

For those just starting out, there is a reduced flat rate (tarifa plana) during the first year of activity. The exact amounts are updated by law, so the prudent thing is to check them on the Social Security website on the very day you register.

What you will file each quarter

This is the real day-to-day life of a self-employed person. Every calendar quarter you will normally file the following forms:

Modelo 303 (VAT). You declare the VAT you have charged your clients and subtract the VAT you have paid on your business expenses. The difference is what you pay to the Tax Agency (or what is refunded or carried forward to offset).

Modelo 130 (personal income tax). This is an advance payment towards your annual income tax, calculated on your cumulative profit for the year. There are cases in which it is not mandatory, for example when most of your invoices already include withholding tax.

Depending on your situation, others may be added, such as Modelo 111 (withholdings on employees or professionals who invoice you), 115 (if you pay rent on business premises) or 349 (transactions with companies in other EU countries). Deadlines generally end on the 20th of the month following the end of the quarter, and the fourth-quarter deadline runs until the end of January. Filing late carries surcharges and penalties.

In addition, once a year you will file your income tax return (Modelo 100) and, where applicable, annual summaries such as the VAT summary, Modelo 390. Also bear in mind that being taxed as a resident or as a non-resident changes your tax framework; as a general reference, tax residence is linked, among other criteria, to spending more than 183 days in Spain in a calendar year.

At Zythos Business we support freelancers and small businesses, including many foreign professionals, throughout this whole journey: from the initial registration and choosing your contribution bracket to the timely filing of every quarterly form and the accounting behind it. If you would rather spend your time on your clients than decoding acronyms, we can get you up and running with everything in order from day one.