Health Minister Rona Ambrose is urging Canadian families who have not yet registered to receive the Universal Child Care Benefit payment to sign up, as almost $3 billion worth of increased payments went out Monday to about 3.8 million families.

"While the majority of families with children woke up today with a little extra cash in their pockets, approximately 200,000 families may miss out," she told reporters at a news conference Monday afternoon. "Today, I urge those families to apply for the Universal Child Care Benefits, because this money belongs to them."

Families who need to sign up can do so by visiting the government website outlining the benefit and other tax credits they may apply for.

The government's UCCB payments to families are considered the largest, one-time benefit payment in federal history, as the increased payments are backdated to the start of the year.

Under the new payment schedule, families with children aged five and under will now receive monthly cheques of $160 per child, an increase of $60 per month. The benefit has also been expanded to include children aged 6-17, providing parents with $60 per child for that age range.

Ambrose said the Conservatives are trying to make life more affordable for Canadian families, and were able to deliver the increased payments as a result of the balanced budget.

"Now that our government has balanced the budget, we're helping your family balance yours," she said.

The Liberals criticized the payments in a news statement released over the weekend, saying the payments are unfair to the middle class and benefit those who need it the least.

Liberal Leader Justin Trudeau told reporters Monday that under a Liberal government, the child care benefit will be a larger, tax-free payment only available for families that make less than $200,000 a year.

Ambrose defended the UCCB payments Monday, noting that the Conservatives believe that when it is possible, the government should return tax money back to Canadians, allowing them to decide how to spend it.

Federal Transport Minister Lisa Raitt echoed this sentiment during a news conference in Mississauga, Ont. on Monday.

"Canadians are telling us the same thing right across the country. It is a challenge to make ends meet," she said. "We want to make sure that life is more affordable for Canadians."

An analysis by The Canadian Press based on the last census shows that most of the benefit payments are heading to ridings where the Conservatives are favoured to win in the upcoming fall election. According to the analysis, many of the ridings receiving the biggest cheques are in suburban Alberta, and ridings surrounding Toronto.

With files from The Canadian Press