I fell foul of it when I was on nil pay sick for a while, but crammed the overtime when I returned to work.
THe bottom line told me by HMRC at the time was "You ended up with taxable pay over £18k for your household, therefore all tax credits paid to you above and beyond the base £10 a week everyone upto £66k earnings gets is forfeit. Since we’ve already paid you £2500 this year, you owe us £2k back by the end of this tax year.
I told them to take the £10 a week residue amount until it is paid in full. I got my letter saying it had finally been repaid last year, so you can work out what year this all happened in I think…
I learned the lesson, and now spend some weeks of each tax year deliberately sitting out as to keep the earnings below the magic £18k threshold.
Tax credits themselves do not count towards your taxable earnings, unlike JSA type benefits which do. This means it is better to NOT sign on every odd week one isn’t working. For instance, I might work 2 x 50 hour weeks in a month, then sit out two weeks in a month making a month aggregate of 25 hours per week average with earnings average of £1k split across that month. Since the aggregate working gross for the year will be £12k, I get and keep the tax credits of well over £5k on top of that, and only pay tax on about 6k of the earnings (because most of us have a tax-free allowance of about 6k), or about £1500 in total. Thus I work only about half the time, receive a net £15500 a year, and get to keep it all without even bothering about JSA and other benefits.
If I did a job paying £25k gross instead, I would end up working flat out to take home barely more money after tax has been deducted, and I’ve forfeited all tax credits that would have topped me up below £18k.
If by some chance one doesn’t get work for about 4 weeks on the spin, it is then worth signing on, as HMRC will stop tax credits once the 4 week rolling average falls below 16 hours (for 2011-2012) and 24 hours (April 2012 onwards) which is a bit of a game changer come April. You would be encouraged to work more full weeks, and sign on even less in the odd unemployment weeks.
It’s a bit like using JSA in the same manner as POA. You don’t do it unless you KNOW you are going to be out of work for at least 2 weeks on the spin.
One week on, one week off throughout the year would mean never having to sign on, and maxing out the tax credits instead which as I’ve said, don’t count towards the taxable pay aggregate in themselves.