While School District of Waukesha officials are offering the teachers union a 0.5 percent base wage increase, the union is asking for a 1.64 percent salary increase for the 2011-12 school year.

An agreement has not yet been reached as the initial proposal from the union was delivered to the School Board on Tuesday.

The salary increase is based on the cost of living increase from the 2010-11 school year, said Cathy Atkinson, president of the Education Association of Waukesha.

But the district won’t be able to negotiate under the union’s proposal, said Gary Ruesch, the attorney for the School Board, because the district can only negotiate for base wages under Act 10’s collective bargaining rules. Because salaries can include supplemental pay, negotiations for salaries do not follow the state law, according to Ruesch.

• See Related: Act 10 Saves School District Nearly $5 Million in Benefit Costs

The wage increases – if an agreement is reached – would be paid to the teachers retroactively. After the 2011-12 contract is settled, school officials can begin work on the 2012-13 contract.

The settling of the past school year’s contracts were delayed because of changes in the state’s Act 10 collective bargaining law that limits public unions from negotiations except for wages. The last contract expired in June 2011. Teachers had wages frozen for the 2009-10 school year and received a 1 percent wage increase in 2010-11.