NedFlanders

What's the simplest way to inform HMRC of NEST and SIPP contributions made in the 23/24 tax year? I know this can't be done by email. Could this be done by phone or webchat? Could I upload the relevant documents securely to HMRC? When HMRC add basic rate tax relief to a SIPP or to a NEST pot, why don't they record it against the personal tax account of the taxpayer who made the pension contribution?