Property capital gains: calculation and reinvestment
In general terms, mais-valias (capital gains) are the taxable gain on the onerous transfer of a property. The calculation starts from the sale and acquisition values, with the legally applicable adjustments. The result is not necessarily the same as the difference between the money received and what was paid for the house. [1–3]
When preparing a sale, it is worth estimating the tax outcome before deciding how much you can put towards the next purchase. The balance left in your account and the gain assessed for IRS (personal income tax) are different calculations.
How to organise the calculation
A simplified representation is: sale value minus corrected acquisition value and eligible expenses. Monetary correction applies under the legal conditions when more than 24 months pass between acquisition and disposal. Documented improvement costs from the last 12 years and necessary acquisition and disposal expenses may be considered under article 51. [2–3]
A purely arithmetical example: assume a sale value of €350,000, a corrected acquisition value of €220,000 and €20,000 of expenses already considered eligible. The gain would be €110,000. This example does not calculate IRS and does not allow you to conclude that every expense of a sale is accepted.
€350,000
Sale value
− €220,000
Corrected acquisition
− €20,000
Eligible expenses
=
€110,000
Gain — not the tax
This example does not calculate IRS and does not mean every expense of a sale is accepted.
Does a €100,000 gain mean paying that amount
No. The assessed gain is a step before the tax is computed. As a rule, the property gain covered by article 43 is taken into account at 50%, with exceptions. That is not equivalent to a 50% tax rate; the final liability depends on your tax position and the other relevant elements. [4]
Reinvesting in a main permanent home
The regime requires cumulative conditions. These include the use of the property sold, stating the intention in the tax return and reinvesting the sale value, net of the eligible loan, in the period running from 24 months before to 36 months after the sale. There are also conditions on tax residence and on the use of the new property. Partial reinvestment may produce a proportional exclusion. [1]
So buying another house of a value similar to the gain is not enough. Prepare a simulation identifying the amount to reinvest, the part financed by a new loan and compliance with the deadlines.
What changed in 2026 for reinvestment in rental
There is a regime for transfers of residential properties made between 1 January 2026 and 31 December 2029, with reinvestment in properties in Portugal intended for residential letting subject to rent caps. It includes deadlines for letting, a minimum tenancy duration and restrictions on selling. It is not an automatic exemption for any property placed on the rental market. [1, 6]
Anyone considering this route should compare the tax benefit with the commitments assumed over the following years and obtain an analysis of their case before investing.
What information to gather for the simulation
Prepare a folder that allows the accountant to reconstruct the transaction without relying on memory:
- Title of acquisition and the property's identifying details.
- Information on the expected price and the costs of selling.
- Invoices and proofs of expenses and works.
- Information on the loan used in the acquisition.
- Relevant dates of residence and use.
- Documents and timetable of the intended reinvestment.
If there are several owners, ask for a simulation per taxpayer. Tax residence, percentages and acquisition history may require different treatment.
Why separate tax from available cash
Planning example: a sale allows the debt to be repaid and a balance to be received. From that balance, agency fees, other costs and tax may still have to come out. Committing the whole amount to the new down payment without this estimate can create a cash need later.
Build two tables: cash movements on the sale and the tax computation. That separation makes the budget for the next stage clearer.
Frequently asked questions
Does repaying the mortgage eliminate the gain
The repaid debt should not be confused with the taxable gain. The loan may be relevant in specific reinvestment regimes, but simple repayment does not replace the calculation analysis.
Does an inherited house have a zero acquisition value
No. The CIRS (personal income tax code) provides its own criteria for assets acquired free of charge, by reference to the value considered, or that would have served as the basis, for Stamp Duty. [5]
Can an expense without an invoice be included
Evidence is essential. Hand the documents to the professional preparing the return and confirm eligibility; do not include an expense merely because it occurred while you owned the house.
Is it enough to declare when the reinvestment ends
The intention and the investments must be indicated in the relevant returns. Plan that follow-up from the year of the sale. [7]
Sources
Next step
Before deciding the price and timetable of your sale, talk to the Valle team to prepare the transaction and gather the information needed for your tax analysis.
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