MI5's budget

MI5's budget is paid from the Single Intelligence Account (SIA) which also provides funding for SIS and GCHQ. 

The SIA's budget is decided by ministers through the Spending Review which helps them decide how much to spend on security and intelligence, in line with the Government’s fiscal rules and decisions on overall spending. 

The Cabinet Secretary is Principal Accounting Officer for the SIA, providing scrutiny on a quarterly basis through the Financial Steering Group, which is attended by the heads of the intelligence agencies and officials from the Treasury. 

Financial oversight 

We are subject to close budgetary scrutiny. Although we have to operate in secret, we account for the money we spend in the same way as other public sector organisations and our accounts are audited by the National Audit Office (NAO). NAO staff have access to relevant MI5 records for this purpose. In addition, our expenditure and resource allocations are scrutinised by the Intelligence and Security Committee (ISC). The ISC's annual reports provide further details of the agencies' funding and expenditure.