Since the T5 slips were extremely slow to update this year, I filed an Taxpayer’s Ombudsman complaint.
Today I received the call from the CRA department responsible. They confirmed that there was a big problem this year. When a filing was flagged for certain follow up, the data was set aside and held for further review. Due to staff error, this data was left in limbo until the mid part of April 2018. As a result, large amounts of T5 data were updated in the last half of April. For example 2 million T5 records issued by TD Bank were not updated until at least 6 weeks after the T5 filing deadline.
I was assured that steps have been taken to ensure this does not happen in the future.