Quantitative Developer (C++ / Python) Day Rate Calculator: Portugal 2026

Your tax treatment depends on your operating structure. Agency: paid through an agency/umbrella that runs your pay exactly like a permanent employee, applying progressive IRS bands plus 11% employee Social Security. Recibos verdes (freelance, simplified regime): a genuinely different mechanic, taxable profit is only 75% of gross revenue (a 25% statutory notional-expense allowance applies automatically), and Social Security is 21.4% on 70% of quarterly income rather than the employee's flat 11% of gross. The calculator above shows both side by side.

Retention rates vary by structure and day rate. Recibos verdes contractors typically retain more thanks to the 25% notional-expense allowance shrinking the IRS taxable base, even though the 21.4% Social Security rate on 70% of income is higher-percentage than an employee's 11%. Agency contractors retain less since IRS applies to the full gross after the agency's fee, with no notional allowance.

Recibos verdes generally nets more thanks to the 25% notional-expense allowance, but this calculator does not model the first-12-months Social Security exemption new freelancers can claim, which would improve early-career recibos verdes take-home further. Agency is simpler and bundles Social Security the way a permanent job would, at the cost of a lower net rate.

At €429/day over 220 billable days, the gross annual contract income is €94K. This is a 82% gross premium over the Quantitative Developer (C++ / Python) permanent salary median of €52K/year. The premium compensates contractors for self-funded Social Security, holiday pay, sick pay, and business overheads a permanent employer covers on an employee's behalf.

At the median €429/day, a Quantitative Developer (C++ / Python) contractor working as a freelancer on recibos verdes takes home about €60,586 a year, 64% of the €94,380 billed over 220 billable days. A permanent Quantitative Developer (C++ / Python) on the €52K median takes home €34,077, so contracting at the median rate leaves €26,509 more a year before unpaid holidays, pension, and gaps between contracts. On take-home alone, contracting draws level with that salary at about €218/day.