Swann, speaking in Calgary, says Prentice needs to rethink a proposed rollback to a tax credit that aids charities.
Prentice plans to cut the Charitable Donation Tax Credit from 21 to 12.75 per cent on donations over $200 in the budget that came out last month.
The government says that will save $90 million a year for a treasury depleted by low oil prices.
But Swann says the rollback is self-defeating given the importance of charitable donations for those most in need.
Swann also says he would like to see more funding for family and community support services.