I think there are two parts to an answer to that question.
The first is that information flow with government departments is generally good, including from the Canada Revenue Agency.
That said, when it comes to actually measuring the tax gap, there are specific datasets that we or anyone would require to actually generate a reliable or reasonable estimate. Currently, the determination by the government and the Canada Revenue Agency, pursuant to section 241 of the Income Tax Act, is that the Parliamentary Budget Officer is not eligible to gain access to that data.