The information requested is not available as HM Revenue and Customs do not hold information on marital status.
Information concerning tax credits customers' appeal rights can be found in the HM Revenue and Customs (HMRC) leaflet WTC/AP “How to appeal against a tax credits decision or award” which is available on the internet at:
www.hmrc.gov.uk/leaflets/wtc_ap.pdf
HMRC is statutorily allowed to examine the correctness of a tax credits claim after it has been finalised. Those powers include time limits for opening an enquiry although there are certain circumstances in which it will still be possible to reconsider a claim for any year after those time limits have expired. Further information can be found in the HMRC Claimant Compliance Manual published on the internet at:
www.hmrc.gov.uk/manuals/ccmmanual/Index.htm