SASKATOON -- Larry Waldinger said he could not believe the large bill he got from the Canada Revenue Agency (CRA).

"When you get a bill for half a million dollars, and you’re a humble bus driver, that's a bit of a shock," Waldinger said.

He said he moved from Saskatchewan to California in 2015. In 2017, after a mistake was discovered on a tax return relating to a property he owned in Saskatoon, the CRA began auditing his taxes from 2015 and the year prior.

In an effort to correct the mistake, he said the CRA asked for more documents. According to Waldinger, at one point the CRA sent him a letter that was incorrectly addressed and he never got it.

"We could have saved a lot of time if they had just sent me an email. Then it probably would have gotten to me and I could have responded more quickly," Waldinger said.

Because of that, communication broke down, and then the big bill came. Waldinger’s account of what ensued was a cumbersome communication process, involving unanswered phone messages, lost contact information, and limited digital communication hindered by things like file size limits.

"I would suggest they modernize. Better communication, better technology," Waldinger said.

The CRA would not comment on this specific case, but in an email to CTV said... "For security reasons the CRA does not use email for taxpayer correspondences, however taxpayers who chose to go paperless can receive electronic correspondence from the CRA via the ‘Secure My Account Portal.’"

The CRA added, they are committed to improving communication, and this month is raising file size limits for uploading documents securely online.

Todd Mackay, Prairie Director for the Canadian Taxpayers Federation, said the CRA needs to ensure security, but also find a way to modernize communication

"Certainly some information is very sensitive and we have to have protections on it. But my bank can do it. So why in the world can't the government? They've got to speed it up, especially when its a complicated situation and the taxpayer is trying to make it right,” Mackay said.

Mackay also said simplifying the tax code could help reduce mistakes.

Meanwhile, after four years, Waldinger is still working through the issue.

"I am still going through it. And I do hope to have it resolved sometime soon. It's been a long, slow painful process."