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

Your tax treatment depends on your operating structure. Enskild firma (sole trader, F-skatt): you pay egenavgifter (self-employed social contributions) of 28.97% on business profit, reduced to 21.47% on the first 200,000 kr of profit for active businesses clearing a 40,000 kr floor, then kommunalskatt and statlig inkomstskatt on the remainder. Egenanställning (umbrella company): the umbrella takes a service fee, pays the standard 31.42% employer arbetsgivaravgift on what's left, then pays out a net salary taxed like a normal employee's. The calculator above shows both side by side.

Retention rates vary by structure and revenue level. Enskild firma often nets more at lower-to-mid revenue thanks to the reduced 21.47% egenavgift rate on the first 200,000 kr of profit, while egenanställning's flat 31.42% arbetsgivaravgift plus umbrella fee can be more competitive at higher revenue once the reduced-rate egenavgift band is exhausted. The calculator above compares both at your actual invoiced revenue.

Enskild firma gives you full control over your own business and can be more tax-efficient at lower revenue thanks to the reduced egenavgift rate, but comes with more admin (bookkeeping, invoicing, F-skatt registration). Egenanställning is far simpler, an umbrella company like Cool Company or Frilans Finans handles invoicing and payroll for a fee (typically 3-8%, the calculator defaults to 6%), at the cost of the standard 31.42% employer arbetsgivaravgift.

At SEK7145/day over 220 billable days, the gross annual invoiced revenue is SEK1572K. This is a 116% gross premium over the Quantitative Developer (C++ / Python) permanent salary median of SEK729K/year. The premium compensates contractors for self-funded egenavgifter or arbetsgivaravgift, holiday pay, sick pay, and business overheads a permanent employer covers on an employee's behalf.

At the median SEK 7,145/day, a Quantitative Developer (C++ / Python) contractor working as an enskild firma takes home about SEK 729,250 a year, 46% of the SEK 1,571,900 billed over 220 billable days. A permanent Quantitative Developer (C++ / Python) on the SEK729K median takes home SEK 537,570, so contracting at the median rate leaves SEK 191,680 more a year before unpaid holidays, pension, and gaps between contracts. On take-home alone, contracting draws level with that salary at about SEK 4,569/day.