The Ontario government says it will introduce legislation this spring to change the way political donations by corporations are taxed.

The province wants to convert an existing tax deduction for contributions by businesses to a non-refundable tax credit.

If approved, the amount corporate donors could get back in the form of a tax credit would remain unchanged at 14 per cent.

The Liberal government says the change is needed because Ontario is harmonizing its corporate income tax system with the federal government's system in 2009.

That means the current tax deduction for corporate donations will expire in the new year.

Contributions eligible for the tax credit include those made to political parties, constituency associations or candidates in a provincial election.

Unused contributions can be carried forward and claimed for up to 20 years.

Ontario's Ministry of Finance says the cost of providing the proposed tax credit would be similar to what it costs under the previous system.