Canadians are all too often getting a busy signal or a message to hang up and try back later when they try to contact the taxman by telephone, says the federal auditor general's latest report to Parliament.

And when they do get through to the Canada Revenue Agency call centre, the report says they are getting bad information more often than the agency has been willing to admit publicly.

The agency has boasted that 90 per cent of callers are able to connect when they reach out for service either through a telephone self-service centre or by speaking to a call centre agent.

But that doesn't take into account the fact that, on average, a taxpayer has to call about four times in a week just to get through to the agency, or the fact that more than half of the calls are blocked outright due to volume, said auditor general Michael Ferguson.

"We found that the agency's numbers didn't account for the 29 million calls it blocked in a year — more than half of its total call volume," Ferguson said.

"Those calls either get a busy signal, a message to visit the agency's website, or a message to call back later."

Overall, only 36 per cent of calls to the tax agency were able to connect, said the report.

"Based on our tests — and those done by others — we found that the Canada Revenue Agency gave taxpayers wrong answers to their questions almost 30 per cent of the time," said Ferguson.

"This rate is significantly higher than the roughly six and a half per cent error rate estimated by the agency."

In its written response to the report, the government said it agreed on the need to improve the accuracy of information provided to taxpayers.

To that end, the CRA said it will launch a new system early next year for training its call centre agents.

It also acknowledged that its current call centre technology is "outdated" and will be upgraded.

Auditor General says CRA didn't consult on wait times1:17