Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Capital Gains on Property
If you sell a property in Portugal, you pay tax on the profit (Mais-Valias). Residents are taxed on 50% of the gain at their progressive IRS rate. Non-residents used to be taxed on 100%, but laws have shifted to equalize this.
You can avoid this tax if you reinvest the proceeds into another permanent home in Portugal (or the EU) within 36 months. You must declare the intention to reinvest in your tax return for the year of the sale.