Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
The Promissory Contract (CPCV)
Before the final deed (Escritura), buyers and sellers sign a CPCV. You typically pay a deposit (Sinal) of 10% to 20%. This contract is legally binding and protects both parties before the bank finalizes the mortgage.
If you back out, you lose your deposit. If the seller backs out, they must pay you back double the deposit amount. Never sign a CPCV without a lawyer reviewing the property's legal history first.