It’s no secret that many wealthy Canadians are squirrelling away fortunes offshore to avoid — or even evade — taxes.

What is secret is just how much money it’s costing fellow Canadians and the national treasury each year.

That’s because unlike many other countries, Canada fails to disclose or even track the full size of its “tax gap” — the difference between the government’s potential tax revenue and what it actually manages to collect.

The U.S. has been tracking and publicly reporting its tax gap for more than 50 years. And now so do more than a dozen other Western countries, including the U.K., France, Germany, Australia, Sweden, Portugal, Mexico, Norway and Denmark.

The Canada Revenue Agency isn’t just keeping data from the prying eyes of journalists.

Find out where some of Canada’s lost tax revenue is going in the Paradise Papers
The agency won’t share what it does know with parliamentarians either.

“It’s shameful,” said Senator Percy Downe of P.E.I. “The Canada Revenue Agency is the most incompetent department … in the government of Canada.”

Downe spoke to CBC News and the Toronto Star, partners in the Paradise Papers collaboration with the International Consortium of Investigative Journalists, which has shed light on the activities of thousands of wealthy individuals and corporations around the globe who use offshore havens to shield money from tax collectors.