An unknown number of taxpayers have been locked out of their Canada Revenue Agency accounts.

When those affected called the agency’s helpline to unlock their accounts, they received little information or no response at all.

A CRA spokesperson says taxpayers registered for online account alerts ”may receive a notification from the CRA indicating that their email address has been removed from their account.”

It was meant ”as a security precaution in the context of ongoing investigative work, and is not due to a cyber security breach of CRA systems.”

The spokesperson says anyone affected can expect a letter in the mail with instructions on how to unlock their account.

There has been no clarification as to the nature of the investigation or why so many accounts had been suddenly locked.

CRA recently said it had hired more call centre agents for what promises to be an exceptionally busy tax season.