Tomás Rius is a sworn German translator in Granada. Since January 2026 he has worked almost exclusively for an agency in Munich, which he invoices about 3,200 € a month, and he also spends 400 € a month on Google ads to find private clients. In April the agency sent one of his invoices back: its accounts department had checked his number in the European system and it showed as "not valid". Tomás had a Spanish tax number (NIF), was registered with Hacienda, as the Spanish tax office is commonly known, and filed his quarterly VAT returns (Modelo 303) on time. What he did not have was registration in the Registro de Operadores Intracomunitarios, the register of intra-Community operators.
A register within the register
The Registro de Operadores Intracomunitarios (ROI) forms part of the Spanish register of businesses, professionals and withholders. Being on it is what turns your Spanish NIF into an intra-Community VAT number: the same number with the prefix ES in front. That number is the one published in the VIES system, the database that businesses across the Union use to check that their supplier or client is an identified operator.
Being registered as an autónomo (self-employed) does not put you on it automatically. You have to ask. Article 3.3 of the Spanish regulations on tax management and inspection (Royal Decree 1065/2007) lists who must be on the register, and for a self-employed person who provides services there are two relevant cases:
- Letter d): businesses or professionals who provide services treated as supplied in another member state when the recipient is the person liable for the tax. That is Tomás's position with the Munich agency.
- Letter c): businesses or professionals who receive services from businesses not established in Spain and are the persons liable for the tax on them. That is Tomás's position with Google, which invoices Spanish advertisers from Ireland.
This second letter surprises many people. You do not need a single client abroad: buying advertising, software or cloud services from a supplier in another EU country is enough to make registration necessary.
Which situations require it and which do not
| Situation | Do you need the ROI? | Why |
|---|---|---|
| You invoice services to a company in another EU country | Yes | Art. 3.3.d) Royal Decree 1065/2007 |
| You buy advertising, software or services from a company in another EU country | Yes | Art. 3.3.c) Royal Decree 1065/2007 |
| You only invoice companies in the United States, the United Kingdom or other countries outside the EU | Not for that reason | VIES is a Union system |
| You only invoice private individuals in the EU for electronic services | It is not what solves your case | That is where the One-Stop Shop comes in, not the ROI |
| You sell goods to or buy goods from businesses in the EU | Yes | Art. 3.3.a) Royal Decree 1065/2007 |
How to apply and how long it takes
You apply on Modelo 036, which since 3 February 2025 has been the only tax registration form (Modelo 037 was abolished). You can apply in the initial registration return itself or later, with a return reporting a change. In both cases you tick the box requesting inclusion in the register and briefly describe the activity and the operators you are going to work with. The guide to registering in the ROI step by step goes through the return.
As for timing, article 25 of the same regulations contains a rule worth knowing: if the Agencia Tributaria, the Spanish tax agency, has not decided within three months, the allocation of the number may be deemed refused. Silence works against you. In practice many applications are decided much sooner, but sometimes the tax authorities first ask for documents proving the activity: contracts, pro forma invoices, a website or emails with clients. If you do not provide them, or they are not convincing, inclusion may be refused. The same article allows this in the cases in article 24.1 and article 146.1.b) of the regulations; the first concerns a check revealing that the details reported are not truthful.
What not being registered was costing Tomás
Suppose Tomás goes from January to April without the ROI. The problem is not where the tax is due: his services to the agency are located in Germany under article 69.One.1 of the VAT Law, because the recipient is a company with its seat there, whether or not he is on the register. The problem is one of evidence and of practice. Let us look at the numbers:
- Invoices to the agency from January to April: 4 × 3,200 = 12,800 €, all without Spanish VAT.
- Those invoices should be reported in Modelo 349, the EU summary return, as intra-Community supplies of services. Without his own intra-Community VAT number, his 349 does not match the information the agency reports in Germany.
- Google advertising from January to April: 4 × 400 = 1,600 €. As the recipient of a service supplied by a business not established in Spain, Tomás is the person liable for the tax (art. 84.One.2 of the VAT Law) and must self-assess it: 1,600 × 21 % = 336 €.
- Those 336 € are declared as VAT due and, at the same time, as deductible VAT in the same 303. The net effect is zero. That is how the reverse charge works.
- The risk is that, if the supplier cannot validate your number, it may treat you as a final consumer and charge you the VAT that applies to a private individual. That VAT cannot be recovered in your 303 through the ordinary reverse-charge route, because the invoice was not issued as a reverse-charge transaction.
And the most visible consequence: without a valid number for its supplier, the German client has no way of showing its own tax authorities that it received the service from an identified operator. That is why the agency sent the invoice back.
Registering in the ROI today does not make invoices from three months ago correct. What it does allow is filing the 349 with your number from then on, regularising the missing periods and, if necessary, reissuing the invoices with the correct VAT number. Filing late returns that were never filed may carry a surcharge; there is no guarantee that putting things right will cost nothing.
If you have already invoiced without being registered
The sensible order is usually this:
- File the 036 requesting inclusion in the register, with documents showing the real activity so as not to give grounds for a refusal.
- Review how you reported that period's transactions in your 303 returns: if the invoices to the agency appeared as not subject to the tax and the purchases from Google with their self-assessed VAT, the VAT was correctly settled even though the registration was missing.
- File the 349 returns for the earlier periods once the number has been allocated. How to work out whether yours is monthly or quarterly is in how often Modelo 349 is filed.
- Explain the situation to the client and, if it asks, send it the decision confirming your registration.
If what went wrong was the self-assessment of your purchases from the EU, the case is different and it is worth reviewing period by period. You can send us the year's 303 returns and a sample of invoices through the form for self-employed people with international clients.
You can also lose the registration
Article 10 of the same regulations requires anyone who has not carried out, in the previous twelve months, any of the transactions that justify being on the ROI to request removal from it, with a return reporting a change. This affects self-employed people who had a European client, lost it and find another a year later: if removal was processed in the meantime, their number no longer shows as valid and they have to apply for inclusion again. Before invoicing a company in another EU country again, it is worth checking your own number in VIES, just as you check the client's.
If your clients are outside the Union and you only buy from suppliers outside it, the register is not what you need. The rules for American clients are in whether I have to charge VAT to a client in the United States.
The relationship between the ROI, the 303, the 349 and the other obligations of people who work for companies in other countries is explained as a whole on the Salama Tax page for self-employed people with foreign clients.