Modelo 111 is the quarterly return for IRPF (personal income tax) withholdings applied to employees' payroll, to professionals who issue invoices with withholding, and to other recipients. It is filed from 1 to 20 April, July and October, with the fourth quarter filed in January, and it involves paying the withheld amounts to the tax agency.
Only those who pay employees or professionals subject to withholding are required to file it, not every self-employed person.
kontora generates your tax forms box by box, tells you how much to set aside and reminds you before every deadline.