In the current tax year, you can earn �5225 without paying any income tax on it. (Since PAYE averages out tax payments over the year, that means that roughly �100 per week of your earnings is free of tax).
You're then allowed a further �2230 per year which is only taxed at 10%. So roughly �43 of your weekly earnings is taxed at this rate.
Unless your annual salary is over �40,035, everything else is taxed at 22%. (Above �40,035p.a. a tax rate of 40% applies).
Here's a rough example for someone earning �300 per week:
First �100, tax rate = 0%. Tax =�0
Next �43, tax rate = 10%. Tax = �4 (to nearest pound)
Remaining �157, tax rate = 22%. Tax = �35 (to nearest pound)
Total tax = �0 + �4 + �35 = �39.
National Insurance contributions basically cut in at above �87 per week, at a rate of 11%. So, an employee earning �300 per week pays nothing on the first �87 and then 11% of the remaining �213. (Roughly �23).
So the total deductions (excluding such things as contributory pension schemes) for an employee earning �300 per week come to about �62. (Roughly 21% of earnings).
For someone earning �500 per week, the figures work out roughly as:
Tax = �0 + �4 + �79. NI = �45.
Total deductions = �128. (About 26% of earnings).
Chris