I'm about to go from earning under the threshold, to completely over it (even with pension contributions factored in) I'm not looking to put more into pension etc to get the amount down. I was wondering if it was just worth continuing to claim it, put it in a savings account and do a self assessment end of the year to pay it all back. I figure I can make a bit of interest off it, and you never know when/if circumstances will change and you can only backdate so much. Am I able to do this? Anything I'm missing that makes this a terrible idea?