Interim Day Rate → Permanent Salary Calculator
Author: Gary Pine · Updated: April 2026 · Market: UK & Europe
Convert your interim day rate to an honest permanent salary equivalent. Three bands — naïve, like-for-like, and risk-adjusted — that price in benefits, bonus, and the security premium.
The Three Bands
Naïve (Day Rate × 220)
Multiplies the day rate by 220 working days. Ignores benefits, bonus, and unbillable time. Always inflated.
Like-for-Like (180-Day Rule)
Day Rate × 180 billable days, less PSC corporation tax and accountancy. Closer to gross take-home reality.
Risk-Adjusted (Permanent Equivalent)
Like-for-like, less the value of pension (8–15%), bonus (15–40%), holiday pay, sick leave, healthcare, share scheme, and the security premium of guaranteed income. Typically 60–75% of the naïve number.
Worked Example: £1,500/day Interim CFO
- Naïve: £330,000 (1,500 × 220)
- Like-for-Like: £270,000 (1,500 × 180)
- Risk-Adjusted: £210,000–£240,000 perm-equivalent base
When the Numbers Lie
If a permanent offer matches the risk-adjusted band plus meaningful equity (LTIP/MIP), the perm route may win on a 5-year NPV. If it matches only the naïve number, you are taking a real-terms pay cut for the security premium.