It’s not quite as sexy as stashing money in offshore tax havens. But Canadians who take advantage of legal tax loopholes here at home arguably cost the federal treasury much more money.

And Finance Minister Bill Morneau is contemplating whether he should close some of these loopholes.

The offshore tax-haven story is making headlines this week thanks to the International Consortium of Investigative Journalists, a group that includes the Star’s Robert Cribb, Tanya Talaga and Marco Chown Oved.

Using information leaked from a Panamanian law firm, the consortium has shone a spotlight on the way Canadians and others use shell companies and foreign tax havens — often in ways that are perfectly legal.

The leaked data contains the names of 350 Canadians.

Exactly what these tax havens cost the public is unclear. Canadians for Tax Fairness, a research and advocacy group, calculates that corporations that openly stash their money abroad in major tax havens cost Canada’s federal treasury just under $8 billion a year.

If individual and surreptitious tax-haven users were added in, that number would be higher

But not all tax avoidance takes place in faraway spots like Panama or the British Virgin Islands.

In 2011, Canadians for Tax Fairness calculated that the public was losing $81 billion a year in revenue generated by what it called the shadow economy.

And in a recently released document, federal finance department estimates indicate that legal loopholes known as tax expenditures will cost the treasury roughly $120 billion this year alone.

While it is not easy to curb either the shadow economy or the use of offshore tax havens, it is technically simple, if politically difficult, to curb tax expenditures.

Morneau did so in last month’s budget when he announced plans to eliminate three loopholes — the children’s fitness and textbook tax credits as well as income splitting for families with young kids.

The budget also promised a comprehensive review of the entire tax system. In a later interview, Morneau told The Canadian Press that this review will focus on tax expenditures.

Certainly there is plenty to focus on.

Corporations will get $1.6 billion in tax breaks this year for research and development. Small businesses will get breaks worth $3.6 billion simply for being small.

Those who sell stocks and other capital assets will get hefty tax breaks, estimated to total $12.1 billion this year.

If that asset is a principal residence, the owner doesn’t have to pay capital gains tax at all — which will cost the treasury an additional $5.3 billion this year.

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For those selling their homes in the supercharged real estate markets of Toronto and Vancouver, this is a particularly delicious tax loophole.

Much has been written about those who pay large sums to schmooze with ministers in Ontario Premier Kathleen Wynne’s government.

What’s not always remembered is that those who make these payments are eligible for political-donation tax breaks, which cost the Ontario treasury an unspecified amount.

The evidence suggests that Registered Retirement Savings Plans (RRSPs) are not a particularly efficient way to encourage Canadians to save for their old age. But this particular tax expenditure is still expected to cost the federal treasury $15.5 billion in 2016.

The politics around tax expenditures are tricky. When Pierre Trudeau’s Liberals took on tax loopholes in 1981, the reaction was so furious that his government was forced to beat an ignominious retreat.

Justin Trudeau could face a similar buzz saw, particularly if Morneau took aim at the sacred cows of the tax expenditure system — such as the $4.4 billion HST credit for poor people or the $2.9 billion break for those who donate to registered charities.

Still, for a government short on cash, there is money to be made from closing loopholes and simplifying Canada’s hideously complex tax system.

By the finance department’s own calculations, combating tax evasion at home and abroad would net Ottawa a relative pittance — less than $500 million a year.

Eliminating or reducing just a few tax expenditures would be, for the government at least, considerably more lucrative.