Tax credit claimants should renew claims by the 31 July deadline or their payments may stop.
HMRC urge claimants to act as soon as they receive a renewal pack. More than 3.3m claimants renewed by the deadline last year, 80% of those who were required to renew their claim.
The department is asking claimants to double-check the accuracy of the information in the pack.
Claimants must also let HMRC know of any changes in their circumstances that they have not already reported. They could be about working hours, childcare costs or pay. If asked, claimants must provide details of the previous year’s income.