Quick answer: the capital gain on the sale of a property corresponds to the difference between the realisation value (sale price) and the acquisition value adjusted by the monetary devaluation coefficient, minus property enhancement costs incurred in the last 12 years and purchase and sale expenses. For residents, only 50% of this net gain is taxed, being aggregated with total income. Full or partial exemption applies when reinvested in a primary residence.
This is one of the areas of IRS (Imposto sobre o Rendimento das Pessoas Singulares – personal income tax) where the most money is lost through lack of knowledge. Not due to tax evasion, but due to failing to keep invoices.
In summary
- Formula: Realisation value − (Acquisition value × coefficient) − enhancement costs − purchase and sale expenses
- Only 50% of the net positive balance is taxed in the case of tax residents.
- The taxable amount is aggregated with total income and subject to progressive IRS tax rates.
- It must be declared in Anexo G (Annex G for capital gains) of the Modelo 3 (annual tax return) declaration.
- Exemption regimes exist for a primary residence (habitação própria e permanente) and for properties acquired before 1 January 1989.
The calculation, step by step
Step 1: realisation value
This is the sale value stated in the deed. If the Valor Patrimonial Tributário (VPT – rateable asset value) is higher than the declared price, the VPT prevails for tax purposes.
Step 2: adjusted acquisition value
The price you paid for the property is updated using the monetary devaluation coefficient published annually by government order, whenever more than 24 months have elapsed between acquisition and sale.
If you inherited the property, the acquisition value is the amount considered for Imposto do Selo (Stamp Duty) purposes. A similar rule applies if you received it as a donation.
Step 3: enhancement costs
Costs incurred in enhancing the property over the last 12 years are deductible, provided they can be proven. This includes refurbishment work, roof replacements, installation of climate control systems, structural alterations, and new kitchens or bathrooms.
Two conditions are non-negotiable: an invoice showing the owner's NIF (tax identification number) and a clear description of the work carried out on the property. A generic receipt for "miscellaneous services" is not valid.
Step 4: purchase and sale expenses
These include, among others:
- IMT (Imposto Municipal sobre as Transmissões Onerosas de Imóveis – property transfer tax) and Imposto do Selo paid on acquisition.
- Deeds, registry fees and notary costs.
- Real estate agency commission on the sale.
- Energy performance certificate.
Practical example
Purchase in 2012 for 150,000 euros, sale in 2026 for 300,000 euros.
| Item | Amount |
|---|---|
| Realisation value | 300,000 € |
| Adjusted acquisition value (illustrative coefficient of 1.26) | 189,000 € |
| Documented work in the last 12 years | 35,000 € |
| IMT and deed fees on purchase | 11,000 € |
| Real estate commission on sale | 15,000 € |
| Capital gain | 50,000 € |
| Subject to IRS (50%) | 25,000 € |
This 25,000 euros is added to the household's remaining income and taxed at progressive rates. Without the invoices for the building works, the capital gain would be 85,000 euros and the taxable amount 42,500 euros. The difference in tax can easily exceed 6,000 euros.
The coefficient used in this example is purely illustrative. The applicable figure depends on the year of purchase and the executive order in force.
Reinvestment in a primary residence
This is the most relevant exemption and the one that raises the most questions.
Essential requirements:
- The property sold must have been designated as the primary residence of the taxpayer or their household.
- The realisation value, minus the repayment of any mortgage taken out to purchase the sold property, must be reinvested in the acquisition, construction, extension or improvement of another property intended for the same purpose.
- Reinvestment must occur within the period between 24 months before and 36 months after the date of sale.
- The intention to reinvest must be declared in the IRS return for the year of disposal.
- The new property must be allocated as the primary residence within the statutory timeframe.
If reinvestment is partial, the tax relief is proportional. Reinvesting 70% of the eligible amount exempts 70% of the capital gain.
Classic reinvestment mistakes
- Failing to declare the intention in the year of sale. Without this declaration, you lose the benefit, even if the reinvestment later takes place.
- Forgetting the mortgage deduction. What counts is the realisation value net of the outstanding mortgage principal repaid, not the total sale price.
- Buying a buy-to-let property. The intended destination must be a primary residence.
- Missing the 36-month deadline. This is calculated from the date of the sale deed.
Other exemptions and special regimes
Properties acquired before 1 January 1989: capital gains resulting from the sale of properties acquired before this date are exempt from IRS tax.
Reinvestment in retirement savings products: a specific exemption regime exists for taxpayers of a certain age or who are already retired who reinvest the sale proceeds into insurance contracts, open pension funds or the public capitalisation scheme, subject to specific conditions.
Housing support schemes: temporary exemption regimes have been created linked to mortgage repayments and the sale of properties to the State or local councils for affordable housing. These measures have specific timeframes and should be checked on a case-by-case basis.
Non-residents
Non-tax residents in Portugal are also taxed on property capital gains obtained in Portuguese territory. Following European case law and subsequent legislative amendments, only 50% of the gain is subject to tax, aggregated with tax rates applied progressively.
For those living abroad, this is an area where interaction with the double taxation treaty of their country of residence is decisive.
Checklist before selling
- [ ] Locate the purchase deed and proof of IMT and Imposto do Selo paid.
- [ ] Gather all invoices for building works over the last 12 years, showing your NIF and a detailed description.
- [ ] Confirm the outstanding mortgage balance at the date of sale.
- [ ] Keep proof of the agency commission and energy certificate.
- [ ] Decide before signing the deed whether you will reinvest and within what timeframe.
- [ ] Check that the property was registered as your fiscal domicile.
Frequently asked questions
Is the entire capital gain taxed?
No. For residents, only 50% of the net positive balance between capital gains and capital losses is considered for IRS purposes.
What works can I deduct?
Costs incurred in enhancing the property over the last 12 years, properly supported by an invoice in the owner's name.
What is the timeframe to reinvest?
Between 24 months before and 36 months after the date of sale.
What if I only reinvest part of the amount?
The exemption is proportional to the amount actually reinvested.
Where do I declare the sale?
In Anexo G of the Modelo 3 IRS tax return, in the year following the sale.
Are you selling or buying a property?
The time to save tax on a capital gain is before the deed is signed, not in April of the following year. At Grupo Your, we simulate the tax impact and help organise the necessary documentation. Speak to us.
Related articles:
- Capital losses in IRS: how to turn losses into tax savings
- IMT 2026: How Much Tax Will You Pay When Buying a House?
- Self-building: how to recover 17% VAT on your house build
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