If you're self-employed in Portugal (Category B income) under the simplified regime, uncategorized expenses in e-Fatura can directly increase your tax bill. This article explains why and how to fix it.
Why this matters
Under Art. 31 nº13 of the CIRS, the tax authority requires that at least 15% of your gross services income is backed by verified professional expenses in e-Fatura.
If your verified expenses fall short of this 15% threshold, the gap is added to your taxable income — meaning you pay more tax than necessary.
Example: - Your services income: 40,000€ - 15% threshold: 6,000€ - Your verified expenses in e-Fatura: 2,000€ - Gap: 4,000€ — this amount is added to your taxable income
By properly categorizing your professional expenses, you can reduce or eliminate this gap.
What counts as a professional expense?
Expenses that directly relate to your professional activity, including:
Office supplies and equipment
Software subscriptions and tools
Internet and phone bills (professional portion)
Coworking space or office rent
Professional training and courses
Travel expenses related to work
Accounting and legal fees
Vehicle expenses (if used for work, with limitations)
How to categorize expenses in e-Fatura
Go to e-Fatura: faturas.portaldasfinancas.gov.pt
Log in with your NIF and Finanças password
Click "Despesas a confirmar" (Expenses to confirm) or "Complemento de informação"
For each uncategorized invoice, select the correct activity sector. For professional expenses, choose "Atividade profissional" from the dropdown
Save each categorization
Important deadlines
You must categorize your expenses before February 25 of the year following the tax year. For example, expenses from 2025 must be categorized by February 25, 2026.
After this deadline, Finanças locks the e-Fatura records and uncategorized expenses cannot be reclassified.
Tips to minimize the gap
Categorize regularly — don't wait until the deadline. Check e-Fatura monthly.
Ask vendors for invoices with your NIF — expenses without your NIF won't appear in e-Fatura.
Mixed-use expenses (like phone or internet) can be partially allocated to professional use. Categorize them as professional in e-Fatura.
Keep receipts — even if expenses appear in e-Fatura, having original receipts helps if Finanças requests verification.
What if I still have a gap?
If your actual professional expenses are genuinely below 15% of your income, the gap will be added to your taxable income. This is normal for businesses with low overhead costs (e.g., consulting, freelance writing). In this case, you may want to consider whether the organized accounting regime would be more advantageous — it lets you deduct actual expenses instead of using coefficients.
What FIZ shows you
In the IRS calculation step, FIZ displays the exact amounts: your 15% threshold, your verified expenses, and the gap. Use this information to check your e-Fatura and categorize any missing expenses before filing.
Related articles: - Organized vs Simplified Accounting: Which Regime Is Right for You?
Legal references: - Art. 31 nº13 CIRS
External links: - e-Fatura portal