I am thinking of contracting, but do not know how to compare contract (inside and outside IR35) with permanent rates, within the United Kingdom (specifically England).

So far I have considered:

That on a permanent contract I worked 5days a week (37.5hours/week), less 25 days holiday and 8 days public holiday.

There are then the different tax schemes.

As a contractor I have to pay employers national insurance at x%

Then there is a 5% something if I am inside IR34.

And expenses, some like mileage have nothing to do with the contract, but are related to permanence of place of work.

Is this correct, and can you help with making it clearer and simpler?

1 Answer 1


There is a permanent vs contractor calculator here that allows you to compare contract rates with permanent rates both inside and outside IR35

  • 1
    (+1) That is pretty good, but does not show assumptions, like how many days leave, hours worked in a day, etc. Sep 19, 2012 at 8:38
  • 1
    I have discovered, today, that If you dig about on this web site the calculations are there. Just click on the hourly rate, to find out how it was calculated. Mar 18, 2014 at 12:52

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