A major Canadian political-finance deadline arrives August 13, with Elections Canada requiring candidates and registered third parties involved in the April 13 federal by-elections to submit their campaign financial returns.

The deadline applies to the three April contests in Terrebonne, Scarborough Southwest and University—Rosedale, elections that helped give Prime Minister Mark Carney's Liberals a parliamentary majority.

The filings can provide Canadians with a closer look at campaign expenses, contributions and political advertising activity surrounding the races.

Elections Canada's rules require registered third parties that conduct regulated activities above the applicable spending threshold to report their contributions and expenses. The reports are made publicly available through the federal election agency.

The new filings could attract particular attention because the April by-elections were politically significant. The Liberals won all three contests, strengthening the government's position in the House of Commons.

For voters, the financial disclosures offer another way to assess how political campaigns are funded and where election advertising money is being spent.

The information may also become useful to political parties and analysts as they examine campaign strategies ahead of future federal contests.