A teacher who finished her training 43 years ago is still stuck on a salary of $59,621 - about $12,000 less than her son, who trained as a teacher 30 years later - because she doesn't have a degree.

Eileen Gilmour says her three years of training at what was then called the Hamilton Teachers' College in 1973-75 covered exactly the same ground as what is now called a Bachelor of Teaching.

"Same courses and papers, same practicums, same everything," she said.

But "the kick in the teeth" was that primary teachers who graduated after the mid-1990s, when the three-year teacher training became a degree, can earn up to $71,891 - about $12,000 more than those who trained earlier.

"It just stinks, I actually feel so under-valued," Gilmour said.

Teachers with a degree, such as Gilmour's own son who did the same teacher training as she did at what is now Waikato University but came out with a degree 11 years ago, reach the top $71,891 base salary after seven years' teaching.

Gilmour has never had a year without teaching since 1975 but has cut back to just relieving, mainly at Tauranga Intermediate and Katikati Primary School, and turned down full-time job offers.

"I'm in a relieving position now because I think, no, I'm not doing this for $59,000, not when teachers are getting $71,000 for a lot less experience," she said.

Some of her friends have given up teaching totally, saying "there's no point" despite the worst teacher shortage in decades.

"There are a lot of people out there who could be put into the system and used," she said. "We might fill some gaps."

The Ministry of Education offered last month to lift the maximum pay for teachers without degrees one step up the pay scale from 2020, and then to lift all teachers' wages by 9.3 per cent, which would give Gilmour a 17.1 per cent pay rise to $69,857 by 2020.

That's more than the 16 per cent pay rise by 2019 being sought by the teachers' union, the NZ Educational Institute (NZEI).

But it would still leave Gilmour, and 2654 other fulltime-equivalent teachers stuck on her current salary, about $9000 below an experienced teacher with a degree, who would get $78,557 by 2020 under the ministry's offer.

NZEI members voted last month to reject the offer and will vote next week on one-day strikes region by region from November 12-16.

"I certainly will be down there with my placard, absolutely!" said Gilmour, who is now 62 and a grandmother of four.

"What they are offering is a jump to step 9 and I agree that's really going to improve things. That's fine.

"But I would like them to just say, 'We mucked up here.' Yeah, I'll accept that [pay rise], but gee, give me some credit, you know! I just want them to say that we did the same training and we need to be called [graduates with] a degree now."

Auckland University's deputy dean of education Dr Wayne Smith said the three-year teaching qualification became a degree in 1996 after the NZ Qualifications Framework was created. But he said the degree programme was not "exactly the same".

"Certainly there wasn't huge change, but the programmes had to be rewritten and restructured," he said.

He said teachers who trained before the change were given an option of retraining for a further year to obtain the degree.

Primary teachers went on strike in 1994 and 1995 to obtain pay parity from 1998 with secondary teachers, who already had to have degrees.

Gilmour said the higher pay rate for teachers with degrees was the price of winning pay parity, but primary teachers never accepted it.

"We were gutted and thought this discrepancy would be put right. Twenty years later it is still a festering sore," she said.

She resigned from NZEI in protest a few years ago.

"I said, 'You are doing me an injustice here, you have gone along with this for 20 years,'" she said.

But when she complained again to NZEI last week, the union said its pay claim this yearincluded removing the qualification-based pay "cap".

"I said, 'Well, you fix this, I might join up,'" Gilmour said.

NZEI president Lynda Stuart, who also trained under the old system in the 1970s but later went back to do a master's degree, said the union had been trying to fix the anomaly for "an awful long time". She believes this is the first time the ministry has agreed to even a partial fix.

Deputy secretary of early learning and student achievement Ellen MacGregor-Reid said there had always been pay scales based on qualification level and Gilmour would have been in the lower bracket of the old three tier system as well.

"The different rates based on qualification and service transferred to the unified pay scale when it was introduced. The unified pay scale merged the three qualification based scales into one scale where the entry and maximum steps within the scale continued to be based on the level of the qualifications held."

She said salaries were currently being addressed through the collective bargaining process.

Salary caps

Today

$59,621 (step 8) with Diploma of Teaching

$71,891 (step 11) with Bachelor's Degree

Ministry offer for 2020

$69,857 (step 9) with Diploma of Teaching

$78,557 (step 11) with Bachelor's Degree

Note: Teachers start on steps 1 to 7 depending on their qualifications, then go up one step a year until they reach their salary cap. They can go above the cap in roles such as syndicate leader or principal.