Hi.Did you keep copies of the repayment claim form and any letter you sent with it? If not, you need to make sure they have your claim. Most post sent to HMRC these days is directed to a centre where it is scanned and viewable by any of the call centres that you might reach when you call HMRC.I'm afraid that successive governments have cut down on staffing levels in HMRC and that is why taxpayers suffer unacceptable delays. I have to say that four months does seem a little long to wait, albeit that many claims will have been made and HMRC hasn't allocated extra staff.If I were you, I'd make a complaint using the guidance here. Sometimes, those who shout loudest get heard. Call the tax office on the number under "Income Tax: general enquiries" here and ask to speak to the complaints manager and then make a verbal complaint giving as much detail about your situation as possible. In my experience, the complaints managers are good at resolving issues. At the very least, they will find out what the backlog is and let you know.The rate of interest paid on income tax overpayments is 0.5% per annum. For a 2014/15 repayment, you won't qualify for interest unless the repayment is made after 31 January 2016.I hope this helps but let me know if you have any further questions.