Teacher pensions are in trouble. The latest figures show that states and districts are half a trillion dollars behind in their commitments to fully fund the retirement benefits they promised teachers. That’s a huge sum affecting some 3.5 million current educators. But not all pension payouts are equal. In fact, just 20 percent of teachers will receive the full amount for which they’re eligible, while tens of thousands each year won’t see a dime of that retirement money.

Thought public pensions were a plush deal that dwarfed those 401(k)s earned by private-sector mopes? Think again, argues two reports released Wednesday by Bellwether Education Partners and the Urban Institute.

“A lot of people believe that pensions are a good way to save for retirement and what this is showing is that the formulas are so back-loaded that very few people will truly reap the benefits of the pension system,” said Chad Aldeman, an associate partner with Bellwether.

The two papers calculate just how unfavorable pension plans are for millions of teachers, particularly those who are younger or leave their employer within a decade. In the typical state, a teacher who changes careers (or, in some cases, moves to a different state to teach) sacrifices $5,000 a year in pension benefits, according to one analysis. That calculation is based on the average starting-teacher salary in each state—which ranges from $26,700 in Montana to $48,100 in New Jersey—and the varying amounts states or districts contribute to public-school teachers’ retirement plans.

In a different calculation, Aldeman and his Urban Institute colleague Richard W. Johnson tallied the number of years a rookie teacher at age 25 would need to work in the same state before the teacher’s pension benefits exceed what he or she put into the plan as an employee. Twenty-five years is what they registered, suggesting that for many educators the pensions may be a worse value than a standard investment account.

Several forces are diluting the economic punch of public-school teacher retirement plans. State and district officials responsible for pensions often call on teachers to wait twice or sometimes three times longer than private-sector employees before they’re eligible for any retirement payout. The minimum number of years teachers must work before becoming eligible for even a portion of their pensions is known as a vesting period. A little over a dozen states, including states with large teacher populations such as Illinois and New York, have vesting periods of 10 years, meaning a public-school teacher in one of those states who leaves his or her teaching job in, say, nine years loses access to significant retirement dollars. In Massachusetts, Aldeman estimates a teacher in this situation would forfeit $105,000. That’s on the extreme end, though: The typical teacher forgoes about $22,000 for leaving before his or her retirement eligibility comes into effect.

Making the financial landscape even less favorable for teachers were decisions some states took during the Great Recession to extend the vesting periods. It was a budget-saving tack that spared the states from some financial bleeding—but it also took a huge toll on teachers, who had already been hit hard by the recession. In many cases educators were also told to contribute a larger share of their income to their pension benefits at a time when salaries barely budged.

To be sure, teachers tend to get a better deal than other public-sector employees. In a separate report from March, Johnson of the Urban Institute noted that police officers and firefighters wait up to 20 years before their eligibility for pensions kicks ins. Also, teachers who quit early are still able to retrieve the money they put into the pension pot.

But those early-departure teachers don’t get reimbursed in full: The contributions they do recover typically exclude any interest bumps those dollars have acquired, as well as any contributions their employers put into the system on their behalf. Meanwhile, teachers who accept new jobs in different states often leave behind portions of their pension wealth because interest gains from one plan don’t fully carry over to the next, according to a 2012 Vanderbilt University brief.

There’s also the strange quirk that affects roughly 40 percent of all public-school teachers: They’re not eligible for Social Security benefits due to a historical peculiarity in which some states theorized pension plans would yield teachers more retirement income than they’d gain from Social Security. Given the option, those states excluded teachers from the government retirement program (as with the private-sector, participating public employees and their employers pay the Social Security tax). For those teachers who retire before their pensions are vested, there’s potential for a double-jeopardy effect —they leave pension benefits on the table and miss out on several years of membership in Social Security.

Private-sector employers that provide retirement plans, like the ubiquitous 401(k), are more generous with their vesting periods, in large part because of federal Employee Retirement Income Security Act regulations. Only Arizona offers immediate eligibility for its teachers, while a handful of states have vesting periods of four years or fewer.

The new reports also break down how many years an average teacher who begins teaching at age 25 would need to work in the same state before her pension benefits are worth more than what she put into the plan. The report’s authors say that just a quarter of public-school teachers in the U.S. will break even with their pensions and that percentage will drop because newer teachers will have greater difficulty extracting value from their retirement plans.

Pension plans for public-school teachers are underfunded by an amount equal to the entire Gross Domestic Product of Norway. So what can public pension administrators do?

One common misconception, particularly given the current state of educators’ pensions, is that these funds rely on new teachers—who devote portions of their paychecks to them but don’t yet reap its benefits—to remain solvent. But Bellwether’s Aldeman rejected that perception, emphasizing that they were “designed to be fully funded upfront so that they can pay benefits in the future.” It’s not the case that pension plans are “designed to be a Ponzi scheme [in which] … new people come in and pay for the benefits of the older workers.” But the shifting financial landscape, Aldeman said, means they’re starting to do precisely that. “What they’ve been using are new teachers … to prop up the existing debt.”

Proposals for reforming state and district teacher-pension policies include reducing vesting periods so that workers don’t lose out on their extra pension money just for changing jobs or careers early. Another quick-fix advocated by some experts would allow teachers who leave the profession early to see larger interest gains for their contributions. But these changes largely reapportion the pension pie on which all teachers rely; it doesn’t enlarge it.

“There’s no free lunch here,” the Urban Institute’s Johnson in an email. “If we’re going to give shorter-term teachers better pensions, we’re going to have to reduce the pensions provided to very long-term teachers. I think that’s a reasonable trade-off.” Johnson has floated the idea of shifting a portion of teacher retirement investments into plans that invest in the stock market and real estate, such as the 401(k). Critics of investment accounts for retirement plans say the fluctuations of the financial market could decimate savings even for the most careful workers.

Still, the way pensions are managed can raise eyebrows, too. While public-finance analysts are tasked with recommending how much money a state should pay into the pension funds to keep them solvent, lawmakers and governors are under no obligation to follow those estimates. One reason for policymakers’ apparent negligence is a lack of incentive: While pension debt isn’t reflected in state budgets, the money allocated to alleviate those debts does come out of the public funds—which may encourage certain state actors to delay payments. Illinois and New Jersey are poster children for underfunding their teacher pension plans by delaying payments.

Retirement woes aren’t limited to teachers, of course. Less than half of U.S. households have any retirement account, and the median amount saved for post-employment life is $2,500 and less than $15,000 for households near retirement age, according to a recent study by The National Institute on Retirement Security.

Public-school teachers account for roughly 2 percent of the entire U.S. workforce and are entrusted with the education of 50 million or so students. In the equation to solve the pension problem, those numbers must weigh heavily, too.