Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Freelancer vs. Company (Unipessoal)
If your annual income exceeds €30k-€40k, switching from Freelancer (Recibos Verdes) to a "Unipessoal Lda" (Single-Member Company) might be tax-efficient. It allows you to deduct more business expenses.
However, a company requires a certified accountant (TOC), which costs €150-€200/month. You also pay Corporate Tax (IRC) on profits. Consult a specialist to calculate the break-even point for your specific situation.