Call HM Revenue and Customs (HMRC) if you think your tax credits are wrong. They can check your award and may be able to change it if it’s wrong.
There’s a different way of disagreeing with an overpayment decision.
If they do not change it or you still think it’s wrong
You can ask for the decision to be reconsidered by filling in a WTC/AP form. This process is called ‘mandatory reconsideration’. You can fill in the form online or print it and send it to HMRC.
You need to do this within 30 days of getting your award notice unless there are exceptional circumstances, for example you were in hospital.
If you disagree with the result
If you’re in England, Scotland or Wales you can appeal to the Social Security and Child Support Tribunal.
If you’re in Northern Ireland appeal to the Appeals Service Northern Ireland.