Form guide
Cambio de base de cotización y comunicación de rendimientos previstos (autónomos)
“Cambio de base de cotización y comunicación de rendimientos previstos (autónomos)” is a procedure of the Seguridad Social (TGSS, Social Security). In 2026 it has 6 deadlines in its calendar: the first falls due on 28 February 2026 and the last on 31 December 2026.
In a nutshell
- Filed with
- the Seguridad Social (TGSS, Social Security)
- For those taxed in
- All of Spain
- How often
- otra
- Deadlines in 2026
- 6, from 28 February 2026 to 31 December 2026
- Official calendar consulted on
- 21 September 2026
Who files it
Text from the official source, in Spanish
Autónomos del RETA que prevén que sus rendimientos netos del año cambian de tramo. Hasta seis cambios al año.
Exceptions and special cases
Text from the official source, in Spanish
- Al darse de alta se comunican los rendimientos previstos en el propio alta (Import@ss).
All its deadlines
Each row is a deadline from the official calendar: the last day to file. When that day falls on a Saturday, Sunday or public holiday, the calendar already moves it to the next working day.
| Period | Last day | Day |
|---|---|---|
| Efectos 1 de marzo de 2026 | 28 February 2026 | Saturday |
| Efectos 1 de mayo de 2026 | 30 April 2026 | Thursday |
| Efectos 1 de julio de 2026 | 30 June 2026 | Tuesday |
| Efectos 1 de septiembre de 2026 | 31 August 2026 | Monday |
| Efectos 1 de noviembre de 2026 | 31 October 2026 | Saturday |
| Efectos 1 de enero de 2027 | 31 December 2026 | Thursday |
Every deadline of the year, month by month: 2026 tax calendar.
Official links
Where it is filed, its instructions and, if there is one, the file format for importing it. All on the website of the Seguridad Social (TGSS, Social Security).
| For | Official link |
|---|---|
| Instructions and help | Bases, tramos 2026 y solicitud de cambio de base |
Frequently asked questions
When does “Cambio de base de cotización y comunicación de rendimientos previstos (autónomos)” fall due in 2026?
According to the official calendar of the Seguridad Social (TGSS, Social Security): Efectos 1 de marzo de 2026, by 28 February 2026; Efectos 1 de mayo de 2026, by 30 April 2026; Efectos 1 de julio de 2026, by 30 June 2026; Efectos 1 de septiembre de 2026, by 31 August 2026; Efectos 1 de noviembre de 2026, by 31 October 2026; Efectos 1 de enero de 2027, by 31 December 2026.
Who does “Cambio de base de cotización y comunicación de rendimientos previstos (autónomos)” apply to?
According to the Seguridad Social (TGSS, Social Security): “Autónomos del RETA que prevén que sus rendimientos netos del año cambian de tramo. Hasta seis cambios al año.”
What happens if “Cambio de base de cotización y comunicación de rendimientos previstos (autónomos)” is paid late?
If the returns were filed on time, the surcharge is 10% if you pay within the month after the due date and 20% afterwards; if they were not even filed, 20% or 35% (art. 30 of the Ley General de la Seguridad Social, the General Social Security Act). The details are in the guide to missed deadlines.
Does Mis Obligaciones do this procedure for me?
No. Mis Obligaciones suggests it in your calendar with the reason, takes you to its official page and reminds you a week before and the day before. The filing is done by you, or your gestoría (tax adviser’s office), on the website of the Seguridad Social (TGSS, Social Security).
Official sources
Where what this page says comes from, consulted on the review date. If something does not match, the source prevails.
- 2026 tax calendar for Mainland Spain and the Balearic Islands Agencia Tributaria
- Bases, tramos 2026 y solicitud de cambio de base Seguridad Social
Keep reading
- 2026 tax calendarThe 164 deadlines of 2026 in Mainland Spain and the Balearic Islands, month by month: the form, the period and the last day, copied from the official calendar. In .ics and .json.
- Filing lateWhat it costs to file a Hacienda form late or pay the Seguridad Social late: 1% per month, 15%, the €200 penalty and the 10% and 20% surcharges.
- Examples7 made-up profiles and the 2026 calendar that Mis Obligaciones’s rules give them: self-employed under direct assessment and under modules, companies, the Canary Islands, Bizkaia and Navarre.
- GlossaryWhat an autoliquidación, the 70% rule, REDEME, SII, IGIC, the Concierto Económico or RETA are, explained in two sentences with their official source.
This is information copied from official sources to help you find your way, not tax advice: your case may have exceptions. Check it on the authority’s website or with whoever advises you.
Your deadlines, and only yours
Tell Mis Obligaciones what you do for a living and it suggests your calendar for the year, each form with its reason. You review it, and it reminds you a week before and the day before.