Both unions are holding consultative, or indicative ballots, on whether they should go ahead with a formal statutory ballot on a one-day unpaid strike which would be held after the Easter holiday. Ballot papers have to be returned by next Thursday.
Currently, teachers can retire on full pension at the age of 60, but the Treasury wants to raise the pension age of all public sector workers to 65 in line with private sector companies. Teachers aged over 52 would not be affected. The minimum age for premature retirement compensation would rise from 50 to 55 for new entrants from next year, and would apply to current members from 2010.
Teachers, however, have argued that the current pension age of 60 should remain in what is a high-stress, demanding job. The unions have accused the Government of moving the goalposts for teachers under the age of 52 who entered the profession in the belief that they would be entitled to retire on full pension at 60. They want current members to have the right to remain on the same terms as they currently enjoy.
The planned changes to the Scottish Teachers' Superannuation Scheme (SSTS) would apply to new entrants from 2006 but would not apply to current pension scheme members until 2013.
While the Treasury underwrites teacher schemes and has effective control of policy, the Scottish scheme is technically separate and MSPs will have to decide on any revised regulations.
Last month, EIS members were urged to write in protest to MPs and MSPs as part of a "day of activity" led by the TUC and STUC over the plans for public sector workers.
According to the EIS, more than 53 per cent of teachers retiring in 2003-04 left before the age of 60, while only 17 per cent clocked up 40 years of service.
David Eaglesham, general secretary of the SSTA, said he feared a serious impact upon teachers' life expectancy. "We will have a bigger, older generation which will be less healthy, and the job won't make that any easier because it is a high-stress job. If teachers have to work until 65, their life expectancy will be reduced."