Labor and the Coalition's plan to increase compulsory employer superannuation contributions to 12 per cent will cost workers up to $20 billion a year in wages once it is fully implemented, new figures show, stinging millions of workers already battling historically low wage growth.

Labor has vowed it will have no more delays increasing super from 9.5 to 12 per cent. The Coalition remains committed to the legislated timetable but has internal reservations about the impact it could have on wages and the financial boost it will give the union and employer linked Industry Super lobby.

The Grattan Institute says increasing superannuation will cost $20 billion in wages. Credit:Dominic Lorrimer

The Grattan Institute will on Friday release a report that shows the cut to wages from raising compulsory super is big.

"Really big," said Grattan's super expert Brendan Coates. "By the time it's fully implemented in 2025-26, a 12 per cent super guarantee will strip up to $20 billion from workers' wages each year, or nearly 1 per cent of Gross Domestic Product."