We’ve covered the car’s VAT on the purchase and on the running costs. What’s left is the other calculation: IRS. And this is where the most common mistake starts - thinking you “write the car off” against the tax. It depends on the regime, and the answers are very different.
Simplified regime: the coefficient already presumes the expenses
In the simplified regime, your taxable profit isn’t “turnover minus expenses”. A coefficient applies (0.75 on art. 151 services, 0.35 on others) that already presumes your expenses. Buying a car does not lower your IRS by its price - there’s no field to “write the car off”.
Where expenses do come in is the 15% test (art. 31(13)): part of the coefficient is conditional on your justifying expenses up to 15% of gross income. But watch two myths:
- It isn’t “recover 15% of the car’s price”. It’s a test that, if expenses fall short, increases your taxable base.
- That test doesn’t count only purchase invoices: the higher of two counts - your specific deduction or, when higher, the mandatory Social Security contributions not already deductible under n.º 2 (the part up to 10% of gross income) - never the two added together.
And here a wrong idea is cleared up: art. 31 does not exclude all car and fuel costs by law. Point e) of n.º 13 expressly includes, for example, electricity, insurance and financial leasing. For costs only partly linked to the activity, n.º 14 sets 25% - not an invented actual percentage.
In practice: in the simplified regime the car rarely moves your IRS - the coefficient is already your “discount”.
Organised accounting: here you do deduct the car
In organised accounting, IRS refers to the IRC rules (art. 32 of the CIRS). Here the purchase, the depreciation and the running costs are different things:
One important difference from VAT: the depreciation limit works as a ceiling on the deductible portion of the cost - not the VAT limit’s “all or nothing”. Going over the value doesn’t wipe out everything; it caps the part you depreciate (art. 34 of the CIRC).
Autonomous taxation: the hidden cost of organised accounting
Someone in organised accounting has a tax the simplified regime does not: autonomous taxation (tributação autónoma) on the car’s charges. Don’t confuse it with VAT or with the 15% rule.
Three warnings about this table: it falls on the car’s charges, not the whole price at once; it does not apply to the simplified regime (n.º 8 excludes it); and it is not the companies’ IRC table - if you have an LDA, the rules are different.
Where FIZ comes in
FIZ prepares your IRS from your receipts, with the right regime, and doesn’t promise you’ll “write the car off” in the simplified regime, where the coefficient already presumes expenses. For organised accounting, the car goes into the books with your accountant.
In summary
- Simplified: the coefficient already presumes expenses; the car doesn’t discount by its price. The 15% test (art. 31(13)) isn’t “15% of the car”, and it includes electricity/insurance/leasing; partial use counts at 25%.
- Organised: you deduct via depreciation + real costs; the depreciation limit is a ceiling, not “all or nothing”.
- Autonomous taxation: organised only; 10-20% by price (€30,000), less on PHEV/LPG, exempt on the 100% electric. It doesn’t apply to the simplified regime or to LDAs.
Last piece: selling, declaring and keeping.
