Day Rate Calculator: What Should You Charge as a UK Contractor?

Your day rate as a UK contractor needs to cover more than just replacing a permanent salary. It must account for the days you do not earn, the costs of running a business, tax, and a buffer for periods between contracts. Here is a framework to calculate it properly.

Step 1: Start with your target annual take-home

Decide what you need to actually land in your bank account after tax. A common target is to match or exceed a comparable permanent salary — but remember, as a contractor you are also building no pension via an employer, receiving no sick pay, and buying your own equipment.

Step 2: Account for non-billable days

You will not work 365 days a year. A realistic working-year calculation for a UK contractor:

• 365 days total
• Minus 104 weekend days
• Minus 8 bank holidays
• Minus 20–25 days holiday
• Minus estimated bench time (gaps between contracts): typically 20–40 days
• Minus sick days buffer: 5–10 days

This leaves roughly 190–210 billable days per year. Use 200 as a conservative baseline.

Step 3: Calculate your gross requirement

Working through a limited company, your tax-efficient income split is roughly:

• Small salary (around the Secondary Threshold, ~£9,100 in 2024/25) to avoid employer NI
• Remainder taken as dividends, which are taxed more lightly than salary

A simplified rule of thumb: to take home £X after tax (assuming a basic-rate taxpayer), your limited company needs to invoice roughly £X × 1.35 to 1.45 to cover corporation tax, dividend tax, and running costs.

For a higher-rate taxpayer, the multiplier is closer to 1.55–1.65.

Step 4: Add business costs

Your invoiced revenue must cover costs before you pay yourself:

• Accountancy fees: £100–£200/month
• Professional indemnity insurance: £500–£2,000/year depending on sector
• Equipment, software, and subscriptions
• Invoicing software (or use Invoa's free plan)
• Training and CPD
• Any office or co-working costs

Example calculation

Target take-home: £70,000/year
Tax gross-up (1.4×): £98,000 revenue needed
Add annual costs (~£6,000): £104,000 required
Divide by 200 billable days: £520/day

That is your floor. If the market rate in your sector is higher, charge more. Day rates are also affected by:

• Specialism and demand (cloud architects and senior developers command £600–£900/day+)
• Contract length (shorter contracts often command a premium)
• Location (London rates typically 20–40% higher than regional)
• IR35 status (inside IR35 contracts pay 20–30% less, to compensate for tax drag)

IR35 and your day rate

If a contract is inside IR35, HMRC treats most of your invoice income as employment income. You pay employee and employer National Insurance and income tax on it. To net the same take-home as an outside-IR35 contract, you generally need to charge 20–30% more on an inside-IR35 engagement — or factor in that the effective rate is lower.

Key takeaways

• Base your day rate on take-home target, not just an equivalent salary
• Use ~200 billable days as your baseline, not 260
• Factor in business costs and tax gross-up (roughly 1.4× for basic rate)
• Adjust upward for specialism, location, and contract length
• Inside-IR35 work requires a higher rate to net the same take-home

Once you have your rate, Invoa makes it easy to invoice at that rate consistently — with day-rate line items, automatic payment reminders, and an audit trail for every client.