Esta pregunta es especialmente importante para aquellos profesionales que están decidiendo si merece la pena darse de alta como autónomos, o para aquellos que una vez que se han dado de baja reciben un encargo inesperado (porque la Ley de Murphy es así).
Can You Legally Invoice Without Being Autónomo in Spain?
Quick answer: Yes, it is possible to issue an invoice without being registered as an autónomo in some limited situations—but only if your activity is genuinely occasional. There is no automatic exemption simply because you earn less than the Spanish minimum wage (SMI). Before issuing an invoice, you'll generally need to register your activity with Agencia Tributaria using Modelo 036, and if your activity is considered habitual, you'll also need to register as an autónomo with Seguridad Social (RETA).
If you're unsure whether your activity qualifies as occasional or whether you should register as an autónomo, it's worth getting professional advice before sending your first invoice.
TL;DR
- You can sometimes invoice without being registered as an autónomo, but only for genuinely occasional activities.
- There is no legal income threshold that automatically exempts you from registering with Seguridad Social.
- If you carry out an economic activity, you'll usually need to register with Agencia Tributaria before issuing invoices.
- Since February 2025, Modelo 036 is the only census registration form—Modelo 037 no longer exists.
- If your activity becomes regular or ongoing, you'll generally need to register as an autónomo and pay Social Security contributions.
- Xolo can help you determine whether you need full autónomo registration and handle the paperwork for you.
Can you invoice without being an autónomo?
Yes—but only in limited situations. Whether you must register as an autónomo depends more on whether your activity is considered habitual than on how much money you earn.
This is one of the most common questions among freelancers moving to Spain. Perhaps you've landed your first client, completed a one-off project, or want to test the waters before starting a business full-time.
Many people assume there's a simple rule:
"If I earn less than the minimum wage, I don't have to become an autónomo."
Unfortunately, Spanish law isn't that straightforward.
Instead, there are two separate registrations you need to understand:
- Agencia Tributaria (the Spanish Tax Agency) – for tax purposes.
- Seguridad Social (RETA) – for Social Security as an autónomo.
They're related—but they're not the same thing.
Do you need to register with Hacienda before issuing an invoice?
In most cases, yes. Before carrying out an economic activity, you'll generally need to register with Agencia Tributaria so you can legally invoice and declare any taxes that apply.
Registering with Hacienda tells the tax authorities that you're starting an economic activity. This registration determines:
- your professional activity (IAE code)
- whether you charge IVA
- whether you pay IRPF through quarterly returns
- which tax forms you'll need to submit
Since February 2025, all new registrations are completed using Modelo 036.
👉 Complete guide to Modelo 036 for autónomos in Spain
The registration process is relatively straightforward, but choosing the wrong activity code or tax obligations can create problems later.
Do you also need to register as an autónomo?
Usually yes if your self-employed activity is carried out on a regular or habitual basis.
Registering with Hacienda doesn't automatically make you an autónomo. Separately, Seguridad Social requires people who carry out a habitual, personal and profit-making self-employed activity to register in the Régimen Especial de Trabajadores Autónomos (RETA).
In practice, authorities consider factors such as:
- how often you invoice
- whether you actively seek clients
- whether the activity is ongoing
- whether you've invested in running the business
- whether the activity resembles a real business rather than a one-off event
No single factor determines the answer on its own.
Does earning less than the minimum wage mean you don't have to register?
No. Since a 2026 Supreme Court ruling, earning less than the SMI is no longer considered a reliable test for avoiding autónomo registration.
For years, many articles suggested that earning less than Spain's Salario Mínimo Interprofesional (SMI) meant you could avoid registering as an autónomo. That was always an oversimplification.
In February 2026, the Spanish Supreme Court clarified that income below the SMI does not automatically mean an activity is non-habitual. Instead, authorities must consider the overall nature of the activity.
In other words: Low income alone is not enough.
Someone earning very little from an activity they carry out every week could still be required to register as an autónomo. Likewise, someone completing a genuinely isolated project may not.
What counts as an occasional activity?
There is no official checklist, but an occasional activity is generally one that is isolated, exceptional and not part of an ongoing business. Examples might include:
- creating a logo for a friend as a one-off project
- giving a single paid workshop
- selling the rights to a photograph once
- completing one consulting assignment without continuing the activity afterwards
By contrast, if you're:
- regularly marketing your services,
- issuing invoices every month,
- working with several clients,
- or planning to grow the activity,
it's much more likely that you'll be expected to register as an autónomo.
There is no "one invoice" rule and no €1,000 exemption in Spanish law.
How do you invoice for an occasional activity?
If your activity genuinely qualifies as occasional, you'll normally need to register with Hacienda before invoicing, issue a compliant invoice and declare any applicable taxes.
A typical process looks like this:
- Register your activity with Agencia Tributaria using Modelo 036.
- Issue an invoice containing all legally required information.
- Charge IVA if your activity isn't exempt.
- Apply IRPF withholding where applicable.
- Submit any required tax returns.
- Deregister your activity if you won't continue working independently.
Even if you don't need RETA registration, your tax obligations don't automatically disappear.
👉 How income tax (IRPF) works for freelancers in Spain
What happens if you invoice regularly without registering as an autónomo?
If your activity is considered habitual and you fail to register, you could face backdated Social Security contributions, surcharges and penalties.
If Seguridad Social determines that you should have been registered, they may require you to:
- register retrospectively
- pay outstanding Social Security contributions
- pay surcharges and interest
- potentially face additional administrative penalties
The longer the activity continues without registration, the greater the financial risk.
What if you already have a salaried job?
Having a full-time job doesn't automatically exempt you from registering as an autónomo. Many people combine employment with freelance work.
This is known as pluriactividad.
If your freelance activity qualifies as habitual, you may still need to register as an autónomo, even if you're already paying Social Security through your employer. Some contribution reductions may apply in cases of pluriactividad, but the registration requirement itself doesn't disappear.
👉 Complete guide to pluriactividad in Spain
When should you simply become an autónomo?
If you're planning to freelance regularly, registering as an autónomo is usually the safest and simplest option. You should strongly consider registering if you:
- expect recurring clients
- plan to invoice regularly
- are actively promoting your services
- expect your freelance income to grow
- want to avoid uncertainty over your legal obligations
While registration involves Social Security contributions and ongoing tax filings, it also gives you legal certainty and access to benefits available to autónomos.
Let Xolo help you get it right
Whether you're issuing your very first invoice or planning to build a full-time freelance business in Spain, getting registered correctly from the beginning can save you time, stress and costly mistakes later.
Xolo helps freelancers registered as autónomos in Spain handle:
- registration with Hacienda and Seguridad Social
- tax filings
- bookkeeping
- invoicing
- ongoing compliance
- access to English-speaking tax experts
If you're unsure whether your activity is truly occasional or whether it's time to become an autónomo, our team can help you choose the right path.
Ready to start freelancing in Spain? Discover how Xolo makes becoming an autónomo simple.
FAQ
Can I issue one invoice without being an autónomo?
Possibly. If the activity is genuinely occasional, you may not need RETA registration, but you'll generally still need to register with Hacienda and comply with your tax obligations.
Is there an income limit below which I don't have to become an autónomo?
No. Spanish law does not establish a fixed income threshold that automatically exempts you from registering with Seguridad Social.
Can I invoice if I have a full-time job?
Yes. However, if your freelance activity is habitual, you may still need to register as an autónomo under the pluriactividad rules.
Do I need Modelo 036 or Modelo 037?
Only Modelo 036. Modelo 037 was abolished in February 2025.
Do I have to charge IVA on an occasional invoice?
Usually yes, unless your activity qualifies for a VAT exemption under Spanish law.
Can I deregister after issuing a one-off invoice?
Yes. If your activity has genuinely ended, you can deregister from Hacienda after meeting your tax obligations.