A $4 trillion hole will need to be filled so Social Security can stay solvent for the next 75 years, regardless of the fate of the suggested private accounts.

At some point, presumably, lawmakers will address the system's long-term financial woes.

As it stands now, by 2017 the system will begin paying out more in benefits than it collects in taxes. By 2041, it will have exhausted its reserves and be able to pay 74 percent of benefits, according to the program's trustees.

Most options involve cutting benefits, raising taxes or a combination of both. Here's a look at some of them, how far they would go toward ensuring solvency and their effect on people:

Raise Social Security taxes.

HOW IT WORKS: Employers and employees each contribute 6.2 percent of the employee's wages, up to $90,000 a year.

HOW IT COULD CHANGE: That rate could be increased.

HOW MUCH IT WOULD SAVE: If employer and employee each paid in 7.2 percent, that would fill 104 percent of the gap.

Tax earnings above $90,000 per year.

HOW IT WORKS: Under the current system, most - but not all - income is taxed. In 2005, Social Security taxes were levied only on earnings up to $90,000 - a number that rises with inflation. About 6 percent of workers earn more than $90,000.

HOW IT MIGHT CHANGE: The $90,000 cap could be raised or eliminated altogether. Currently, retirement benefits are based on how much workers paid into the system. If Congress raised the tax cap, it could increase benefits to match the increased taxes, or it could raise the taxes without increasing benefits. Lawmakers could also leave the cap at $90,000 but increase taxes for earnings over, for example, $200,000.

HOW MUCH IT WOULD SAVE: Eliminating the cap without raising benefits to match the increased taxes for high-income workers would raise more than needed to make the system solvent for 75 years, plugging 116 percent of the hole.

Eliminating the cap and raising benefits to match would plug 93 percent of the gap.

Raising the cap to about $145,000 and increasing benefits for those paying more payroll taxes would fill 40 percent of the gap.

Raise the retirement age.

HOW IT WORKS NOW: Retirement age is now 65 1/2 , slowly rising to 67. Workers can retire as early as age 62 but with reduced benefits.

HOW IT COULD CHANGE: Under one version, the retirement age would rise faster, and eventually reach 68. Under a second plan, the retirement age would eventually reach 70.

HOW MUCH IT WOULD SAVE: The first version would plug 28 percent of the gap; the second, 36 percent.

Reduce payments by changing the formula used to calculate initial benefits.

HOW IT WORKS: Benefits are set based on a complicated formula that takes into account how much money a worker made each year. Earnings from past years are adjusted to current dollars based on the rate at which wages have increased. This is called wage indexing.

HOW IT COULD CHANGE: Adjust annual wages based on the rate at which prices have risen, known as price indexing. Because prices rise more slowly than wages, benefits would fall. If this option were fully put in place, benefits would be 46 percent lower. An alternative would be to make this change for upper-income workers, phase it in for those in the middle and keep benefits the same for those at the bottom.

HOW MUCH IT WOULD SAVE: Changing the system for everyone would more than fill the gap, raising 111 percent of needed cash.

Curtail annual cost-of-living benefit increases.

HOW IT WORKS: Once initial benefits are set, they rise each year with the consumer price index to keep pace with inflation.

HOW IT COULD CHANGE: The annual increase could be reduced by using an alternate measure of inflation, which would reduce annual increases by about 0.22 percent.

HOW MUCH IT WOULD SAVE: Fills about 15 percent of the gap.

Reduce benefits as life expectancy rises.

HOW IT WORKS: The current formula for setting benefits does not take into account the fact that people are living longer.

HOW IT COULD CHANGE: The benefit formula could be configured to cut payments for each new class of retirees as life expectancy for their age group rises.

HOW MUCH IT MIGHT SAVE: Depending on the formula change, it could fill 25 percent to 50 percent of the gap.

Bring state and local workers into Social Security.

HOW IT WORKS: About 25 percent of state and local employees are covered by alternative pension systems.

HOW IT COULD CHANGE: The government could require new state and local workers to enroll in Social Security.

HOW MUCH IT WOULD SAVE: About 10 percent of the gap would be plugged.

Invest a portion of the Social Security trust fund in the stock market.

HOW IT WORKS: The Social Security trust fund is now invested in Treasury bonds, which have almost no risk but a low rate of return.

HOW IT COULD CHANGE: Rather than give individual workers the power to invest their money in stocks, the government could invest part - 15 percent, for instance - of the trust fund in equities.

HOW MUCH IT WOULD SAVE: If 15 percent of the trust fund were invested, 15 percent of the gap could be filled, depending on returns.