Your agency must raise self-billed invoices for all transactions with your PSC named on the document for a period of up to twelve months (or the duration of the contract).
The agency will need to complete self-billed documents showing the PSC name, address and VAT registration number, together with all the other details that make up a full VAT invoice. The PSC should retain all these details and be able to produce them for inspection to HMRC VAT if required.