What your records have to contain to survive a check by Autoridade Tributária e Aduaneira, and the rate DriveHub applies.
€0.40 per km
In force 2024-01-01 onwards.
The boletim itinerário / mapa de deslocações. The rate ceiling for own-car use comes from Portaria n.º 1553-D/2008; CIRS art. 2.º makes the excess taxable.
Two clocks, and which one applies is a distinction the app already models. A regime simplificado filer keeps the supporting documents for the four years following the year they relate to — CIRS art. 128.º n.º 3, a duty to produce within 15 days on demand. Anyone on organised accounts or VAT-registered, which includes every employer holding a boletim itinerário, is on ten years from the end of the year of the record (DL 28/2019 art. 19.º n.º 1, CIVA art. 52.º n.º 1), extended further wherever the caducidade of LGT art. 45.º runs longer. Portugal is the long outlier of its neighbourhood — ten years against Spain's four-to-six. Failure attacks the exemption itself rather than the excess: CIRS art. 2.º n.º 3 al. d) taxes the allowance as category A "quando não sejam observados os pressupostos da sua atribuição", and the employer loses the deduction under CIRC art. 23.º-A n.º 1 al. h). RGIT fines run €150–€3 750 for non-exhibition and €225–€22 500 for keeping no records at all.
The excess over the ceiling, or an unsupported claim, is taxed as employment income.
The requirements above are quoted from Portugal's own tax authority. DriveHub keeps them, and the rate, under version control and re-checks them against the authority's pages — this page is generated from that record, not written separately from it.
DriveHub records this automatically. It tracks each drive in the background, keeps the start and end, the distance and the route, and exports a report in the shape a tax office expects.