The NAO's financial audits give assurance over three aspects of government expenditure: the truth and fairness of financial statements; the regularity (or statutory validity) of the expenditure, and; the propriety of the audited body's conduct in accordance with parliamentary, statutory and public expectations.

The NAO is subject to inspection by the Audit Quality Review team of the Financial Reporting Council.

"Good Governance", an output somewhere between financial and VFM audits, was previously a strand of NAO work, but is no longer a focus of activity.

The Exchequer Section is also responsible for agreeing payments from the Consolidated Fund directly to certain bodies, including the King (through the civil list) and judicial salaries.

The earliest known mention of a public official responsible for auditing government expenditure is a reference made in 1314 to the Auditor of the Exchequer.

[3] The Commissioners worked closely with the Comptroller of the Exchequer (who was charged with controlling the issue of funds to the government) following the establishment of that office in 1834.

The NAO developed from the former Exchequer and Audit Department[1] (founded in 1866) in 1983 as the auditor for central government (including most of the externalised agencies and public bodies) as part of an "appropriate mechanism" to check and reinforce departmental balance and matching of quantitative allocation with qualitative purpose (as set out by public policy).

Part of the NAO's London Office is a listed building, originally built for Imperial Airways as their "Empire Terminal".

[6] The building is a modern, open plan office and the refurbishment enabled the NAO to introduce many environmentally friendly features, such as rain-water harvesting.

Following the controversy over a previous C&AG's expenses (see Criticisms) the governance arrangements of the NAO were overhauled and a Board was put in place to oversee the running of the organisation.