In Ontario alone, winning lottery and instant-play tickets worth a total of $21.4 million expired without ever being cashed in at the end of the Ontario Lottery and Gaming Corporation's 2014/2015 fiscal year, OLG spokesman Don Pister told CBC News.
Although it's a large amount of money, it represents just over one per cent of a total $1.8 billion won in the province that year, Pister said.
"The vast, vast majority of lottery prizes are claimed," Pister said. "Lottery players by and large do a great job of checking their tickets shortly after a draw."
Under OLG rules, players have one year to claim their winnings.
Most of the unclaimed prizes are small amounts ranging between $2 and $100, he noted, which add up to the millions.
"It could be a $5 prize on a [Lotto] 6/49 ticket that gets stuck in a purse or a glove box," Pister said. "Or a two- or four- or 10-dollar prize on an instant ticket that someone scratches and ... doesn't get around to going to a retailer and claiming those smaller prizes."
According to the OLG, it's rare for winners not to claim major prizes, which it defines as $10,000 or more.
The last jackpot that went unclaimed was a $5-million prize won in a Lotto 6/49 draw on March 29, 2004, Pister said. It expired after one year.
That hadn't happened since 1989, he added, when the winner of a $4.5-million prize didn't come forward.
Ontario is not alone in having large amounts of unclaimed money. As of February 23, for example, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland had a combined total of $2.4 million in unclaimed winnings from regional draw games, according to the Atlantic Lottery Corporation (ALC).
The prizes, which could still be claimed, are worth between $1 and $100,000, said ALC spokeswoman Christine Manore in an email to CBC News.
But that amount did not include winnings from Canada-wide lotteries, she noted, because those are operated by a national body on behalf of provincial and regional lottery corporations. ALC did not have information available on how much national prize money had gone unclaimed in its provinces, Manore said.
What happens to the money?
For cross-Canada draws, like Lotto Max and Lotto 6/49, unclaimed and expired prize money goes back to the national fund to be used in future draws or promotions, according to both Pister and Manore.
The rules for unclaimed money from provincial or regional draws and games appear to vary.
In Atlantic Canada, unclaimed prizes from games only available in that region, including Tag, Twist and Salsa Bingo, "are used in part for subsequent lottery draws or promotions to ensure that unclaimed wins go back to players in the form of prizing," Manore said.
For Ontario-only lotteries and games, such as Lottario and several scratch-and-win games, unclaimed money goes back to the provincial government, Pister said.