If you made a big charity donation in the past few years in exchange for a hefty tax return, many times greater than your donation, you may be the victim of a huge tax scheme, and Canada Revenue Agency officials are about to catch up to you.

Helping fight AIDS in Africa is the focus of a group called the Canadian Organization for International Philanthropy (COIP). You donate money that's used to buy AIDS drugs and in return you get a huge tax refund.

Bernie Boudreau donated close to $20,000 in 2008.

"It all looked good and I thought, well finally there's a decent tax break and it looked good when the CRA gave T5 slips and that was the selling feature for myself," said Boudreau. 

Bernie got a shock when four years later, the Canada Revenue Agency sent him a letter to say it was denying that 2008 claim stating "this was not a valid gift pursuant to the Income Tax Act" and that the “financing arrangement was a sham.”

Bernie was ordered to repay the money in full, plus interest, which amounted to another $1068. 

"I regret this big time. Had I known this was a scam, I wouldn't have got involved whatsoever,” said Boudreau.

Bankruptcy trustee Blair Mantin is seeing lives financially destroyed by tax shelter schemes.

"I think it’s just morally offensive,” he said. “It just makes you angry that they're still able to this with impunity even though so many people are staying up late at night just trying to worry about how they're ever going to deal with a tax bill like this."

Boudreau is far from alone in getting caught up in this tax shelter scheme.

The Canada Revenue Agency tells CTV News that, "in recent years, approximately 10,000 individuals per year participated in gifting tax shelter arrangements."

To date, 182,000 Canadian taxpayers who donated to one of these tax shelter schemes have been reassessed. Nearly $6 billion in donation claims have been denied.

Boudreau thinks the Canada Revenue Agency is partially to blame.

"They're giving these T5 slips out, and then they're denying them after you've filled your taxes out," he said.

Boudreau wonders why these tax shelter companies are allowed to continue operating.

"I lost a lot of trust, and shame on the government of Canada for that, it seems so corrupt," he said. 

So what is the Canada Revenue agency doing to protect taxpayers? Tune in to CTV News on Tuesday to find out.