If you think a decision about your working tax credit is wrong, you can ask HM Revenue and Customs (HMRC) to look at it again. This process is known as a ‘mandatory reconsideration’. Provided you ask within the time limit (usually 30 days), HMRC notifies you of the decision in a ‘mandatory reconsideration notice’. If you are still not happy when you get this notice, you can appeal to the independent First-tier Tribunal. If it was not possible to ask HMRC to reconsider the decision within 30 days, you can ask for a late review (within 13 months), explaining why it is late. You can also ask HMRC to look at a decision again at any time if certain grounds are met – eg, if there has been an official error.