What is alta?
Alta means you’re officially starting your activity as a self-employed worker. It involves registering with:
Agencia Tributaria (AEAT) using Modelo 036, to tell them what type of activity you’ll do and under what tax regime
Seguridad Social to start making monthly social security contributions under the RETA system
You must do both before you issue your first invoice. No backdating allowed.
What is baja?
Baja means you’re stopping your self-employed activity. You file:
Modelo 036 again with AEAT to notify the tax office
A separate form (usually online) with Seguridad Social to stop paying your monthly cuota
You need to do this if you’re stopping work for a while or closing down completely. If you don’t file your baja, you’ll keep getting charged Social Security even if you’re not earning.
Can you go on and off?
Yes, many autónomos register and deregister multiple times throughout the year, especially if their work is seasonal or irregular. Make sure you file properly each time to avoid fines or surprise bills.
