The PDCA was introduced in 1991 to assist former Prime Ministers still active in public life. Payments are made only to meet the actual cost of continuing to fulfil public duties. The costs are a reimbursement of incurred expenses for necessary office costs and secretarial costs arising from their special position in public life. Let me assure you that this is not an annual salary and it is not paid to support former Prime Minister's private or parliamentary duties. 

The PCDA has a financial limit, which is currently set to £115,000 and has remained frozen since 2011. The level of the limit will be reviewed by the Prime Minister at the start of a Parliament and annually thereafter. 

Copies of all supporting documentation, i.e. salary details, receipts/travel cards for the former PM, or any of their staff, should be made available on request by either Cabinet Office Finance or the National Audit Office for audit purposes. 

The annual amount received by each PDCA claimant is published each year in the Cabinet Office Annual Report and Accounts. Here is the link to the publication for 2021 22 - https://www.gov.uk/government/publications/cabinet-office-annual-report-and-accounts-2021-22