rebatable

You are either going to have to increase the EITC (a form of rebatable tax credit as DTM mentioned above) or do something about payroll taxes.

Matthew Yglesias » McConnell’s Middle Class 2009

I believe it's correct to say that the Conservative position is that the public per-vote subsidies should be eliminated, but that the political parties should be treated as other non-profit organizations and be permitted to apply for GST rebates, the value of which would reduce the amount of their rebatable paid election expenses.

The story the mainstream media buried! Except… never mind - Inkless Wells - Macleans.ca 2009

SECRETARY RUBIN: In order to provide this as a tax cut, it would be a tax credit that is rebatable.

Budget Briefing By Administration Officials ITY National Archives 1999