To register as self-employed in Spain, complete two procedures before starting: tax census registration on form 036 and RETA registration with Social Security. Both should use a consistent start date. Prepare your IAE and CNAE codes, activity address, earnings forecast, contribution base, mutual insurance provider and bank account. Form 037 has not existed since February 2025.
Registering as self-employed in Spain is not a single procedure. Before starting, you need to coordinate two records: census registration with the tax authority and self-employed registration with Social Security. Both should describe the same activity and show a consistent start date. Completing only one leaves the other half of your obligations uncovered.
This guide explains the map and sequence, not which box to tick in every individual case. Your activity, customers, territory and tax regime can change the answer.
Before registering: define the activity and start date
Start by describing what you will actually do and from which day. That description decides your Economic Activities Tax (IAE) heading, CNAE code and much of what you must declare. Avoid choosing a code merely because its label sounds close: one profession can contain different activities, and you may need to report more than one.
The start day is not decorative. It is the point from which contributions and the related tax duties begin. The tax authority requires registration before the activity or operations start, while the Treasury lets you apply up to 60 calendar days in advance. Prepare both procedures around a realistic date, before issuing the first invoice or providing the service.
Step 1: tax census registration with form 036
Entry in the Census of Business Owners, Professionals and Withholders is reported on form 036. The former simplified form 037 was abolished on 3 February 2025; any guide that still tells you to choose between 036 and 037 is out of date. For individuals, the tax authority now provides assistance within form 036 to identify the activity and fill in the related regimes.
This step reports, among other things:
- the start date, address and place where the activity will be carried out;
- the IAE heading or headings that describe what you do;
- the applicable income-tax regime and any instalment-payment duties;
- your VAT position and, where relevant, withholding duties.
These choices are not a generic checklist that every freelancer should tick. Not every activity charges VAT, for example, and not everyone under direct assessment files form 130. If a box depends on an exception or the type of customer you serve, settle that question before registering. As an alternative, some entrepreneurs can route the procedures through a Business Support Point using Spain’s Single Electronic Document.
Step 2: RETA registration through Importass
Once the tax activity is identified, register under the Special Scheme for Self-Employed Workers (RETA). Importass asks for the IAE and CNAE codes, activity date and address, plus a forecast of net earnings. You will also select a contribution base within the applicable band, a collaborating mutual insurance provider and an account for direct debits.
The forecast is not an unchangeable promise: it establishes your initial contribution position and can be updated when the business changes. Keep the registration receipt and check that the date, activities and contact details match what you reported to the tax authority.
Reduced contribution: check eligibility before relying on it
The relief commonly called the “flat rate” appears in official procedures as the reduced contribution. Being newly self-employed is not enough by itself: eligibility depends on requirements, earlier registration periods and possible incompatibilities. Its amount and conditions can also change between years.
This guide therefore does not state a universal amount. Check the current condition in Importass when you register and request the relief within that process if you qualify. Building the first months’ budget around the reduction before the Treasury recognises it can give you a false picture.
What becomes active from day one
| Area | What to keep under control |
|---|---|
| Invoicing | Numbering, required details, VAT and withholding where applicable. |
| Records | Income, expenses and evidence linked to the activity. |
| Taxes | Only the forms and periods arising from your census registration. |
| Contributions | Monthly contribution, earnings forecast and changes of activity. |
If your activity carries VAT, the quarterly VAT calculator helps explain the balance between output and input VAT. If you use direct assessment and owe instalment payments, see the form 130 guide. The exact dates for each tax year are in the tax calendar.
Aurio can help organise transactions and estimate figures, but it does not file forms or complete registrations with the tax or Social Security authorities.
Common mistakes
- Assuming that tax registration automatically includes Social Security registration.
- Starting to invoice and leaving the procedures until the end of the month.
- Looking for form 037 in old instructions even though it is no longer in force.
- Choosing an approximate activity heading without checking the duties it triggers.
- Reporting different dates or failing to communicate every activity.
- Budgeting for a reduced contribution before confirming eligibility.
- Forgetting that books and supporting documents start with the first operation.
Frequently asked questions
Does form 037 still exist for registering as self-employed?
No. The Spanish tax agency abolished form 037 with effect from 3 February 2025. Census registration now uses form 036, which includes the simplified assistance previously offered through form 037.
Can I register after starting the activity?
You can report a late registration, but it will be treated as out of time and may mean losing contribution benefits, owing contributions from an earlier date, surcharges or penalties. The safe rule is to complete both registrations before starting.
Do I need a separate registration for every activity?
Social Security has a single self-employed registration even if you carry out several activities. Each activity must still be correctly reported to both the tax authority and the Treasury, with its codes and start date.
Can Aurio submit these registrations for me?
No. Aurio is an informational tool: it helps you understand and estimate obligations, but it does not register you or file returns with the Spanish tax or Social Security authorities, and it is not a substitute for an accountant.
