Ontario is urging the federal government to help them clamp down on corporate tax dodging.

Ontario Finance Minister Charles Sousa is asking for help to close loopholes that allow corporations to avoid paying taxes by shifting their profits and losses across Canada.

He says it could bring in $200 million by 2017, according to the commission that made recommendations last year on how Ontario could slay its $12-billion deficit.

In his letter to Finance Minister Jim Flaherty and Revenue Minister Gail Shea, Sousa says some companies also shift profits earned in Ontario to foreign subsidiaries to avoid paying tax.

Sousa says he also wants federal help to crack down on the growing underground economy, which deprives the province of tax dollars and makes it difficult for legitimate business to stay competitive.

The province needs Ottawa's help because the federal government collects about 75 per cent of Ontario's tax revenues.