Modelo 036 is the census registration form used to register, update or deregister a self-employed activity or company with the Spanish tax agency, covering the economic activity, VAT regime and other tax details. It must be filed before issuing the first invoice and updated whenever those details change, since it determines which other tax obligations apply.
A simplified version, Modelo 037, exists for individuals who meet certain conditions and do not need to complete every section of the 036.
kontora generates your tax forms box by box, tells you how much to set aside and reminds you before every deadline.