5.4.4 Self-assessment models
The model 303 will be submitted quarterly between April 1 and 20, July and October and between January 1 and 30 of the following year . If in any quarter there is no amount to be paid, a declaration for the last period must also be submitted.
If payment is made by direct debit, the submission will be made online between April 1 and 15, July and October and between January 1 and 25 .
In addition, an annual summary declaration must be submitted, in form 390 , together with the final self-assessment, unless they are exempt from submitting this summary declaration.