For public sector workers across the country, the difference of a couple of years, months or even days when starting on the job could mean the loss of hundreds of thousands of dollars in retirement benefits.

Facing ballooning bills and strained budgets, 45 states have either cut pension benefits or increased mandatory employee retirement plan contributions, or both, since 2009.

While some of the changes and cutbacks impact current state workers and retirees, the most significant ones affect new hires. As a result, those who become firefighters, teachers, garbage men or other public sector workers after the cuts go into effect will end up with considerably smaller nest eggs.

Take California: A state highway patrol officer hired before September 2010 can retire at age 50 after 30 years on the job with 90% of his salary. At an average salary of $100,000, that would translate into a pension of $90,000 a year. But if that same officer was hired this year instead, his annual retirement check at age 50 would total $60,000. That's a $900,000 difference over the course of a 30-year retirement.

In New York, a public employee hired in April 2012 or later will retire with benefits that are roughly 11% lower than someone hired a month earlier, according to the National Conference of State Legislatures. In Pennsylvania, workers hired in 2011 or later will contribute the same chunk of their paychecks to their pensions as those hired before them but will receive about 20% less come retirement.

And in Alabama, state employees hired this year will have to work longer to qualify for retirement benefits that will be roughly 20% lower than those promised to workers hired last year -- although new employees will contribute slightly less out of each paycheck.

Benefits for employees who are already on the payrolls are contractually obligated so major changes would require making an agreement at the bargaining table. Some state laws even bar the reduction of benefits for current employees, leaving new hires as the main targets for cost cuts.

"These people are not at the table; they do not have a voice," Center for Retirement Research Director Alicia Munnell and Rebecca Cannon Fraenkel said in a January report on cuts to teacher pension plans.

Proponents say that the cuts trim excessive benefit levels, especially among top earners who have retired with six-figure pension checks.

"(Pensions) are taking away from the essential services that our constituents need and deserve," New York City Mayor Michael Bloomberg said in a speech in Albany, N.Y., last year. "We see how they're increasing our tax rates all across this state, money that's coming out of the pockets of people who are working hard trying to make ends meet."