This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Child Benefit Technical Manual

Guardian's Allowance: Claiming - Amending claims

Child Benefit & Guardian’s Allowance (Administration) Regulations 2003,regulation 8

Anyone who has made a claim to Guardian’s Allowance may amend it by notifying the appropriate office in writing, as long as the appropriate office (see CBTM12001) is notified before a decision has been made on the claim.

Her Majesty’s Revenue & Customs may treat a claim amended in this way as if it had been so amended when it was first made