The supplementary estimates are tabled as a document in the same form as Part II of the main estimates. However, instead of being expressed as summary votes (i.e., where a vote summarizes all the anticipated disbursements in a particular expenditure category), each supplementary estimate or vote relates to a specific program or financial transaction. The information included in the supplementary estimates becomes a schedule in the subsequent Appropriation Act authorizing the prescribed withdrawals from the Consolidated Revenue Fund.
Supplementary estimates are tabled when the amounts voted under the main estimates prove insufficient, or when new funding or a reallocation of funds already authorized is required during a fiscal year.
Funds are reallocated within a given estimate by using a budgetary device called a “dollar item”, which does not involve the appropriation of new funds.
As with the main estimates, each set of supplementary estimates is normally presented to the House by the President of the Treasury Board and is accompanied by a recommendation from the Governor General, which the Speaker reads aloud in the House.
Supplementary estimates are deemed referred to the relevant standing committees immediately after their tabling in the House.
The supplementary estimates must be reported back, or are deemed to have been reported back, not later than three sitting days before the last allotted day, or the last sitting day, of the supply period in which they were tabled.
Final supplementary estimates usually cover the period from December 10 to March 31 of the fiscal year to which they apply and are normally tabled with the main estimates for the incoming fiscal year. They are usually concurred in on the last supply day of the period ending on March 26.
Where concurrence in final supplementary estimates cannot be obtained before March 31 of the fiscal year to which they relate, the Standing Orders provide for approval to be sought in the next supply period, which is the first supply period of the subsequent fiscal year.
In such cases, three days are added to the supply period ending not later than June 23 to consider the motion that the House concur in those final estimates for the previous fiscal year and to pass at all stages any bill based thereon.