These set out the Government’s formal annual spending plans for each department, and their agencies and arms-length bodies. The Main Estimates are normally presented to Parliament in April for approval by the House of Commons in early July (in the event of a general election in the Spring/early Summer the Estimates are usually presented to Parliament in July).

The advance funding approved through the earlier Vote on Account is deducted from each departmental estimate and the remainder (known as the ‘balances to complete’) is approved through Supply resolutions. These Resolutions are then given legal effect through a Supply and Appropriations (Main Estimates) Act. This legislation provides the legal basis for the issuing of money from the Consolidated Fund in accordance with the requested sums and spending limits set out in the Main Estimates.

These are the Government’s additional requests to Parliament to authorise new funding levels (or amend existing ones) and/or authorise changes in the purpose for which money is sought by departments. Supplementary Estimates are used, for example, to address costs arising from transfers of functions in machinery-of-government changes.

Supplementary Estimates are usually published in February for approval by the House of Commons in Supply resolutions by 18 March, to enable the funds to be spent before the end of the financial year. The Supply resolutions are then given legal effect in a Supply and Appropriation (Anticipation and Adjustments) Act.

These are exceptional requests made by the Government if a department spends money beyond the level or purpose approved by Parliament. In effect, MPs are asked to grant retrospective approval for the spending. Statements of Excesses are exceptional spending requests, not the norm, and usually arise as a result of an error, or where unavoidable spending has been incurred. Any such Statement automatically triggers a qualified audit opinion by the National Audit Office and a Public Accounts Committee report.

The graphic below - compiled by the House of Commons Library - sets out where the Main Estimate and Supplementary Estimates and the accompanying Supply and Appropriations Bills fit in a normal financial cycle.