Every month a payment to the Seguridad Social (social security) is debited from an autónomo‘s (self-employed person’s) account. People call it the quota, the rate or simply social security; its official name is the cuota.
The state does not set this amount. It equals 31.5% of a figure you chose yourself when registering as autónomo. That figure is called the contribution base (base de cotización). Most people leave it at the minimum when they register and never come back to it.
If your income changes, you can change the base — and the payment changes with it. You do this yourself in the Importass online account, in a few minutes. You can change it up to six times a year.
How income turns into a payment
It is easiest to explain with an example. An autónomo earns €1,450 net a month.
Step one: income determines the band. €1,450 falls into the band from €1,300 to €1,500. These bands are called tramos, and there are 15 of them. You do not choose the band — it follows from your income.
Step two: each band has a range. For this tramo the base can be anything from €960.78 to €1,500. This is where the choice is yours.
Step three: the payment is 31.5% of the base. At the minimum base it comes to €302.65 a month, at the maximum €472.50.
The difference is almost €170 a month on the same income. This is what you control. The slider in your online account moves the base within the range; it does not move you into another tramo.
Why pay more than the minimum
The contribution base determines not only the payment but also all the benefits you may receive: sick pay, maternity and childbirth benefit, the cessation of activity benefit and your pension.
A minimum base means a minimum payment and minimum protection. Saving a hundred euros a month today affects the amount of sick pay if you need it tomorrow. This is a conscious choice, not an optimisation.
When the change takes effect
The year is divided into six application windows. The date you click the button only determines which window you fall into. There is no “two months from the application” countdown: an application on 1 July and one on 31 August give the same result.
| Application submitted | New base applies from |
|---|---|
| 1 January — last day of February | 1 March |
| 1 March — 30 April | 1 May |
| 1 May — 30 June | 1 July |
| 1 July — 31 August | 1 September |
| 1 September — 31 October | 1 November |
| 1 November — 31 December | 1 January of the following year |
The base cannot be changed retroactively. An application submitted on 1 September will only take effect from 1 November — for two months you pay on the old base.
Step by step: how to change the base
- Open the Seguridad Social website and go to the Importass section.
- Log in to your account. Cl@ve, a digital certificate or SMS login all work.
- Open Cuota y cotización. In the general catalogue of services the same service is called Base de cotización y rendimientos and is found under Altas, bajas y modificaciones.
- Click Modificar.
- Enter your forecast of average monthly net income. The system will show you which tramo you fall into.
- Move the slider and choose your base. The payment is recalculated immediately, next to the slider.
- Confirm the application and save the justificante — the confirmation as a PDF.
One interface detail people trip over: the screen shows two ranges. Go by the limits labelled Tramo de bases de cotización — these are the ones that restrict your choice.
If you have a gestor with power of attorney, they do the same thing using the Solicitar como apoderado button.
Table of bases and payments for 2026
The table has been carried over unchanged from 2025. Only the rate went up: the intergenerational equity mechanism (MEI) rose from 0.8% to 0.9%, and the total rate became 31.5%.
| Net income per month | Base: from — to | Minimum payment |
|---|---|---|
| up to €670 | €653.59 — €718.94 | €205.88 |
| €670 — €900 | €718.95 — €900 | €226.47 |
| €900 — €1,166.70 | €849.67 — €1,166.70 | €267.65 |
| €1,166.70 — €1,300 | €950.98 — €1,300 | €299.56 |
| €1,300 — €1,500 | €960.78 — €1,500 | €302.65 |
| €1,500 — €1,700 | €960.78 — €1,700 | €302.65 |
| €1,700 — €1,850 | €1,143.79 — €1,850 | €360.29 |
| €1,850 — €2,030 | €1,209.15 — €2,030 | €380.88 |
| €2,030 — €2,330 | €1,274.51 — €2,330 | €401.47 |
| €2,330 — €2,760 | €1,356.21 — €2,760 | €427.21 |
| €2,760 — €3,190 | €1,437.91 — €3,190 | €452.94 |
| €3,190 — €3,620 | €1,519.61 — €3,620 | €478.68 |
| €3,620 — €4,050 | €1,601.31 — €4,050 | €504.41 |
| €4,050 — €6,000 | €1,732.03 — €5,101.20 | €545.59 |
| from €6,000 | €1,928.10 — €5,101.20 | €607.35 |
The maximum base in the system is €5,101.20 a month. Even with income well above €6,000 you cannot pay contributions on a higher amount.
How net income is calculated
Net income (rendimientos netos) is neither turnover nor what arrives in your account.
For an autónomo under estimación directa (direct assessment) the calculation is: income for the year minus deductible expenses, plus the social security contributions paid during the year, and then minus 7% of the result for general expenses. The result is divided by 12 — this is the average monthly net income you enter in the application.
For an autónomo societario (self-employed company director) the general expenses deduction is 3% rather than 7%. There is also a floor: the base cannot be lower than €1,000, regardless of income.
If you are on the reduced rate
In their first year of activity most new autónomos pay a reduced rate — the tarifa plana, also known as the cuota reducida. It is a fixed amount, not a percentage of the base.
So while you are on the reduced rate, changing the base does not change your monthly payment. The slider moves, but the amount stays the same. This often causes confusion.
The base still matters, though — benefits and your contribution record are calculated from it. And there is a separate scenario worth knowing about in advance: if your income grows beyond the threshold in the second year of the reduced rate, the concession is withdrawn and contributions are recalculated according to your actual tramo for the whole period. The difference can run into thousands of euros. In this situation it pays to give up the reduced rate in advance (renuncia a la tarifa plana) and switch to a normal base.
If you are also an employee
When you combine employment with being autónomo (pluriactividad), contributions are paid twice — by your employer and by you. If your total contributions for common contingencies exceed the threshold set for the year, part of the overpayment is refunded.
The refund does not always arrive automatically — you have to request it. This is one of the most common unnoticed overpayments among people who registered as autónomo without leaving their job.
What happens at the end of the year
During the year you pay based on your forecast. After you file your IRPF (personal income tax) return, Hacienda passes data on your actual income to the TGSS (General Treasury of Social Security), and your contributions are recalculated. This is called regularización.
There are three possible outcomes. Your forecast matched reality — nothing happens. You paid more than your actual income required — the difference is refunded. You paid less — the difference is charged and you are given a deadline to pay.
Hence the main practical rule: understating your base does not save money, it postpones the payment. If your actual income turns out higher than forecast, you will have to pay the shortfall in full and all at once.
The reverse is also true. If the year is going worse than forecast, it makes sense to lower the base in good time rather than wait a year and a half for a refund.
When to get advice
Changing the base yourself is enough in a simple situation: one type of activity, clear income and no debts to the TGSS.
It is worth looking into things separately if you have pluriactividad, if you are on the reduced rate and your income is growing, or if you combine being autónomo with a stake in your own company.
