You work from home and pay rent, electricity, and internet. You know those costs are directly related to your work — but you’ve never deducted them from your tax return.
You should start. It’s legal, simple to calculate, and can represent hundreds of euros per year.
The basic rule: the area proportion
The logic is straightforward: you can deduct the percentage of housing costs that corresponds to the area you use for work.
Calculation:
Office area ÷ Total home area = % deductible
Example: You have an 80 m² flat and use a 12 m² room as an office.
12 ÷ 80 = 15%
You can deduct 15% of each eligible housing expense.
What’s deductible
| Expense | Deductible? |
|---|---|
| Rent or mortgage payment | ✅ Yes |
| Electricity | ✅ Yes |
| Water | ✅ Yes |
| Internet and telephone | ✅ Yes |
| Building maintenance fee | ✅ Yes |
| Maintenance works | ✅ Yes |
| Home insurance | ✅ Yes |
| IMI property tax (if owner) | ✅ Yes |
| Personal furniture | ❌ No |
| Food | ❌ No |
Example with real figures:
Pedro has an 80 m² flat with a 12 m² office (15% proportion):
- Rent: €700/month → €700 × 15% = €105/month → €1,260/year
- Electricity: €60/month → €9/month → €108/year
- Internet: €35/month → €5.25/month → €63/year
- Water: €25/month → €3.75/month → €45/year
Total deductible: €1,476/year
The space must be dedicated
The tax authority requires a clearly identified space used primarily for work. Working from the sofa and deducting half the living room doesn’t count.
What works:
- A separate office (room with a door)
- A bedroom converted into an office
- A fixed corner of a room with a dedicated desk and shelving
What doesn’t work:
- “I work anywhere in the house”
- Space that also serves as a bedroom at night
Practical tip: Take photos of your workspace and keep them. If the tax authority asks for justification, you have visual proof.
What to keep
- Lease contract or deed (if owner)
- All electricity, water, internet, and gas bills
- Floor plan or room measurements
- Photos of the workspace
The tax authority can request justification for up to 4 years. Scan everything and store it in the cloud.
Special cases
Shared housing: If you share with others and split the rent, calculate the proportion based on your portion. If the total rent is €1,200 and you pay €600, the calculation uses €600.
Hybrid working (home + client’s office): If you only work from home part of the time, you can adjust the percentage proportionally.
Property owner: Instead of rent, you can deduct the IMI property tax and maintenance costs, using the same proportion.
⚠️ Reasonable limit: You never deduct 100% of housing costs, even if you work exclusively from home. The reasonable limit is around 25–30% of total housing expenses, depending on the size of your workspace.
How to log this in FIZ
In FIZ’s expenses module, you log each housing bill under the “Home Office” category and apply the corresponding percentage for your situation.
The system:
- Calculates the deductible amount automatically
- Aggregates it into your total professional expenses for the year
- Compares it against the automatic 25% coefficient
- Alerts you when your real expenses exceed the simplified regime’s automatic deduction
When it’s time for your income tax return (Annex B, expenses field), the figures are ready — without a single manual calculation.
✅ In summary
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The formula is simple: office area ÷ total home area = % deductible. Apply that percentage to your rent, electricity, water, and internet bills.
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The space must be dedicated and identifiable — working from the sofa doesn’t count. Take photos and keep all documents for at least 4 years.
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With FIZ you log expenses once, set the proportion, and the system calculates and aggregates automatically. At year-end, the figures are ready for your tax return without a single manual calculation.
