Self-employed fee 2026: adjust your base before September 30 and avoid surprises with Social Security

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How to adjust your contribution mid-year, avoid negative regularizations, and align the fee with the reality of your business. With the regularization process of the previous year underway and the upcoming deadline of September 30 to modify the contribution base, it is time to assess whether your actual income for 2026 matches your initial forecast. This practical guide explains how the income brackets system works, the impact of current fees, and the steps to manage your base with Social Security, thus ensuring financial control of your activity and avoiding surcharges or unexpected payments.

Self-employed fee 2026: adjust your base before September 30 and avoid surprises with Social Security

If your billing in 2026 is different from what you anticipated in January, you have until the September 30 to modify your contribution base (effective from October 1). Adjusting your fee to the actual income bracket avoids unforeseen regularizations and unnecessary surcharges.

Summary scale of brackets and bases (2026)

To choose your fee, you must locate your forecast of monthly net income in the official table. Here are the brackets grouped with their minimum bases (on this base, 31.20% is applied to obtain what you will pay per month):

Net income per month Minimum base to apply
Up to 900 € Between 653.59 € and 750.00 €
From 900.01 € to 1,500 € Between 845.00 € and 960.60 €
From 1,500.01 € to 2,030 € Between 980.00 € and 1,030.00 €
From 2,030.01 € to 3,190 € Between 1,050.00 € and 1,100.00 €
From 3,190.01 € to 4,050 € Between €1,130.00 and €1,160.00
More than €4,050 Between €1,200.00 and €1,750.00
(Note: The maximum base for all those who exceed €1,166 in income rises to €4,720.50)  

2025 regularization letter: what to do?

Social Security is now notifying the adjustments from the previous year after cross-referencing data with the Tax Agency:

  • If you overpaid: They will automatically refund the difference.

  • If you underpaid: You will receive a payment letter. Doing it outside the voluntary deadline implies a surcharge of 10% (20% if it goes to executive proceedings).

How to calculate your correct base in 4 steps

  1. Net income: Subtract your deductible expenses from the accumulated income of the year and project the total over 12 months.

  2. Legal deduction: Apply an automatic discount of 7% (self-employed individual) or 3% (corporate).

  3. Locate your bracket: Divide the resulting amount by 12 and locate your bracket in the table above.

  4. Compare: If your current fee does not match that bracket, request the modification.

Quick procedure in Importass

 

  1. Enter the portal Importass of the Social Security with Cl@ve, DNIe or digital certificate.

  2. Go to Personal area > Contributions > Modify contribution base .

  3. Choose the bracket corresponding to your actual income and confirm.

 

 

Things to consider: Lowering your monthly fee relieves your business's immediate treasury, but reduces the amount of your future benefits for medical leave, cessation of activity, or retirement.

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