A Calgary lawyer says an increasing number of Americans living abroad are renouncing their U.S. citizenship because of a recently passed tax law.

Tax lawyer Roy Berg says since the Foreign Account Tax Compliance Act law was enacted a few years ago, the number of Americans living abroad who are giving up their U.S. citizenship has been going up.

He's been holding free seminars across the country explaining the pros and cons of such a decision - including one in Calgary Friday.

Roy Berg says last year about 3,000 Americans renounced their citizenship globally and that’s expected to jump to 4,000 this year. (Colleen Underwood/CBC)

"The number of renouncers keeps going up and up and up," Berg tells CBC News.

The law requires banks from around the world to sift through their accounts to look for clients with U.S. connections then share that information with the U.S. Internal Revenue Service.

That's why Berg says renouncing seems appealing to some people.

"It could save them money and certainly save them hassle and save them filing obligations and save them from paying accountants and lawyers to prepare and file tax returns that most of the time had no U.S. taxes owing," Berg explains.

Darrin and Melanie Wiebe are among a crowd of about 50 people attending the seminar.

She's from Texas, he's Canadian and runs a business.

"Right now the way the tax law works, it's probably worth a few hundred thousand dollars what we end up having to pay, if we abide by the law in the U.S.," Darrin said.

"In the end … we'll end up paying extra."

The Wiebes say they're not sure yet whether the financial gains might be worth some of the potential risks which includes getting permanently barred from the country if the process is not done correctly.

Tammy Adams came to learn more about taxation and relinquishing her citizenship.

Tammy Adams says she has been thinking about giving up her U.S. citizenship for a while now. (Colleen Underwood/CBC)

"I've been thinking about it for a while and now I'm thinking a lot harder about it because of all the taxation issues involved in it," Adams said.

"And the fact that Canada is home for me now. This is going to be my forever home."

Berg says last year about 3,000 Americans renounced their citizenship globally and that's expected to jump to 4,000 this year.

According to the U.S. State Department there are about 7 million U.S. citizens who live outside the country. It's estimated that between 700,000 and 2 million live in Canada.