How long does it take to file the Modelo 210 myself?

With a structured platform such as Fiscaro, a standard case generally takes 15 to 30 minutes — provided all documents are to hand. Have ready: NIE number, IBI assessment (with cadastral value, Referencia Catastral and Año de revisión), ownership share, days of ownership, and for rental income the rental receipts for the tax year. If any information is missing, the time required increases accordingly. Directly through the AEAT's Sede Electrónica, considerably more time should generally be expected — beyond obtaining the digital certificate or Cl@ve, familiarity with the form fields and IRNR codes in Spanish is required. For mixed use (rental plus self-use) or multiple co-owners, the effort increases proportionally — each additional declaration requires its own pass, even though much of the base data is identical.