Taxpayers will be on the hook for millions of dollars if Prime Minister Harper cancels four byelections this month by calling a general election, according to Elections Canada.

Elections Canada estimates a federal byelection would cost an average of $892,000 per riding.

So taxpayers could potentially be left with a bill for almost $3.5 million, as campaign spending starts from scratch if a byelection is cancelled.

With three of the byelections scheduled for next Monday, it's likely little money will be recovered.

"If a byelection is in full swing, and even if we're two days before a polling date and it gets cancelled, we start off again, we close the book on the byelection and start off in general election mode," said John Enright, spokesman for Elections Canada, in an interview with the Canadian Press that was published Wednesday.

This means the amount that could be recovered from the money already spent on the four byelections "would be minimal," said Enright.

The total cost of running a byelection also includes reimbursing the candidates for 60 per cent of their expenses, provided they receive at least 10 per cent of the vote.

But if the byelections are cancelled, Elections Canada will pay all the candidates' expenses not covered by donations.

The prime minister is widely expected to call an election by this weekend, with voters going to the polls Oct. 14.