The Canada Revenue Agency said Wednesday its online tax filing system was back up and running.
The federal government department said it has resolved the technical issues that prevented people from filing their 2006 tax returns.
"The CRA's processing systems are back online," commissioner Michel Dorais said in a statement on the agency's website. "All of our databases have been restored, our online services have been tested to our satisfaction, and our employees are processing the backlog of returns and payments.
"I would like to thank taxpayers for their patience and understanding during this unprecedented service outage," Dorais said.
Dorais had ordered the agency's 75 databases shut down March 5 after noticing "some irregularities" following software maintenance the previous weekend.
All online access to Efile, Netfile and the My Account feature was affected by the shutdown.
The CRA said the processing of returns — including the issuing of refunds — was delayed until the problem could be fixed. The processing delays also affected paper-based returns that were mailed.