Just a heads up to check your personal tax account (Gov site) if you are a supply teacher working with more than one agency. I checked today and my 'estimated taxable income' was quite considerably higher than usual and discovered they had 'estimated' an additional 11K or so through an agency I haven't worked with for 2+years! Hopefully will be sorted and usually receive any over the top tax as a rebate during the Summer holidays which can be especially helpful this time of year, when not paid and for example, you have to buy a 'new' used car as happened last year, despite also working full time over the Summer Holiday! Having a different estmate I don't think automatically affects whether you will/have actually paid too much tax but it may affect tax-free earning amount and may adjust figures. While they're trying to encourage more people to use the online site - and to be fair it does appear to be fairly straightforward, you can still just ring them up and ask them to check too. IF I hadn't done this last year in August/September, I would not have received 2K rebate. Also don't fall for the companies that encourage you toto use them instead as you can just check and claim yourself.