Canadians trying to file their tax returns using Netfile have had their deadline extended from midnight Wednesday to May 6 due to problems with the Canada Revenue Agency's website.

Taxpayers using Netfile recently have encountered delays with the website and in some cases have not been able to file at all. Canada Revenue Agency spokesman Peter Delis told CBCNews.ca the situation appeared to have improved by Wednesday afternoon. He blamed the problem on the big spike in online filings in the final days leading up to the tax deadline.

A notice announcing the filing extension was posted Tuesday on the Canada Revenue Agency's website.

"If you have difficulty sending or correcting your Netfile return, you have until midnight (local time) on Tuesday, May 6, 2008, to transmit it," the notice says. "Your tax return will be considered as filed on time."

However, if you owe money to the government for your 2007 taxes, you still have to send the money by the usual April 30 deadline — that's Wednesday midnight. The CRA said mailing a cheque with a postmark showing Wednesday's date would qualify as being on time.

Users of Efile — the internet-based filing system used by those who prepare tax returns for a living — have also been granted an extension to May 6, but balances due must still be sent by the end of April.

Many returns to come

The Canada Revenue Agency said that, as of Sunday, there were still almost eight million Canadians who hadn't filed.

The tax department is expecting about 25 million tax returns. As of April 28, about 17.1 million returns have been processed.

Those who file late and owe the government money face a five per cent penalty. As well, debt not paid by April 30 results in interest charges of one to two per cent every month.

Sending in tax returns electronically has become the most popular way to file. The CRA said that so far in 2008, nearly 10.4 million Canadians have filed their income taxes using that method, a half-million more than were filed electronically at the same time in 2007.

More than 6.3 million paper returns have been received and nearly 415,000 returns have been filed by telephone.

The government has already sent out a total of 11 million refunds to Canadians who filed, with an average refund of $1,411 — up $170 from last year at this time. Retroactive tax increases contained in last year's fall economic update explain that increase.

In March 2007, the Canada Revenue Agency experienced an online tax filing system outage that lasted about eight days. The system was ordered taken down after some irregularities were found following software maintenance.