The self-employed in Spain have been warned they could face fines of up to €12,000 if they start working before being officially registered with Social Security (Seguridad Social).

The government body has updated its guidance for autonomos, reminding anyone starting a self-employed activity that they must register with the Special Regime for Self-Employed Workers (RETA) from the very first day they begin trading.

Those who fail to do so risk hefty financial penalties, backdated social security payments and the loss of valuable contribution discounts.

According to the updated guidance, anyone found to have started working before registering could face fines ranging from €3,750 to €12,000, depending on the seriousness of the offence.

They will also be required to pay all outstanding Social Security contributions dating back to when the authorities determine their business activity began.

Anyone registering late will be treated as having been registered from the first day of the month in which they eventually regularise their situation, but they will lose access to any reduced-rate contributions or bonuses they might otherwise have qualified for.

It’s not about how much you earn

One of the biggest misconceptions among new autonomos is that they do not need to register if they earn less than Spain’s minimum wage (SMI).

Employment lawyer and ATA Valencia president Alberto Ara says that is largely a myth.

‘The key factor is not income, but whether the activity is habitual,’ he told Diario A y E.

Someone who opens a bar every day, for example, must register regardless of whether the business earns more or less than the minimum wage.

Where the confusion came from

Much of the misunderstanding stems from a 1997 Spanish Supreme Court ruling, which used earnings as one indicator when determining whether someone was genuinely carrying out self-employed work.

However, Ara stresses that the court did not establish the minimum wage as a legal threshold below which registration was unnecessary.

Instead, it was simply one factor considered in a very specific case where there was little other evidence of whether the work was carried out regularly.

Other exceptional court cases involving retired self-employed workers or occasional agricultural work have also helped fuel the misconception.

The rules changed in 2023

Since Spain introduced its income-based contribution system in 2023, experts say the argument about earning below the minimum wage has largely become irrelevant.

People with very low incomes can now access lower contribution bands instead.

In 2026, those earning less than €670 per month are assigned a minimum contribution base of €653.59, resulting in a monthly Social Security payment of around €205.

What happens if you register late?

If you delay registering, Social Security will calculate your contributions from the date it believes your business activity actually began.

For the period before registration, contributions are calculated using the minimum contribution base of the general table, which in 2026 is €950.98.

Those payments will not count towards the annual contribution regularisation process, meaning late registration can prove significantly more expensive than registering correctly from day one.

For anyone planning to become self-employed in Spain, experts say the safest approach is to register before you begin working or issuing invoices, rather than trying to regularise your situation afterwards.