A cost-sharing formula specifies how costs for shared projects or programs are divided among participating governments or organizations. In Canadian infrastructure funding, a common formula is 33-33-33, with federal, provincial, and municipal governments each contributing one-third. However, formulas vary based on program, project type, and jurisdiction. Some programs provide higher federal shares for small municipalities with limited fiscal capacity. Formulas may be based on population, tax base, benefit received, or other factors. Cost-sharing formulas significantly affect municipal finances—more generous senior government shares mean municipalities can accomplish more with their available resources. Advocating for favourable cost-sharing is a key municipal priority.