As you work and pay taxes, you earn " credits" that count toward eligibility for future Social Security benefits.

You can earn a maximum of four credits each year. Most people need 40 credits (10 years of work) to qualify for benefits. Younger people need fewer credits to qualify for disability or survivors benefits.

Your Social Security benefit is a percentage of your earnings averaged over most of your working lifetime.

Social Security was never intended to be your only source of income when you retire or become disabled, or your family's only income if you die. It is intended to supplement other income you have from pension plans, savings, investments, etc.

Low income workers receive a higher rate of return than those in the upper income brackets, but a worker with average earnings can expect a retirement benefit that represents about 40 percent of his or her average lifetime earnings.

To get a free estimate of the retirement, disability and survivors benefits that would be payable to you and your family, call Social Security at 1-800-772-1213 (TTY users should call 1-800-325-0778) or use one of our Benefit Calculators.

Retirement

Benefits are payable at full retirement age (with reduced benefits available as early as age 62) for anyone with enough Social Security credits. The full retirement age is 65 for persons born before 1938. The age gradually rises until it reaches 67 for persons born in 1960 or later. People who delay retirement beyond full retirement age get special credit for each month they don't receive a benefit until they reach age 70.

Disability

Benefits can be paid to people at any age who have enough Social Security credits and who have a severe physical or mental impairment that is expected to prevent them from doing "substantial" work for a year or more or who have a condition that is expected to result in death.

In 2011, earnings of $1,000 or more per month are generally considered substantial. The disability program includes incentives to smooth the transition back into the workforce, including continuation of benefits and health care coverage while a person attempts to work.

Family Benefits

If you are eligible for benefits based on your earnings, other members of your family could also qualify for benefits based on your retirement or disability. These include: your spouse if he or she is at least 62 years old or under 62 but caring for a child under age 16; and your children if they are unmarried and under age 18, under 19 but still in school or 18 or older but disabled. If you are divorced, your ex-spouse could be eligible for benefits on your record.

Survivors

When you die, certain members of your family may be eligible for benefits if you earned enough Social Security credits while you were working. The family members include: a widow or widower age 60 or older, 50 or older if disabled or any age if caring for a child under age 16; your children if they are unmarried and under age 18, under 19 but still in school or 18 or older but disabled; and your parents if you were their primary means of support.

A special one-time payment of $255 may be made to your spouse or minor children when you die. If you are divorced, your ex-spouse could be eligible for a widow or widower's benefit on your record.

Medicare

There are two parts to Medicare: hospital insurance (sometimes called Part A) and medical insurance (sometimes called Part B). Generally, people who are over age 65 and getting Social Security automatically qualify for Medicare. So do people who have been getting disability benefits for two years. Others must file an application.

Part A is paid for by a portion of the Social Security tax of people still working. It helps pay for inpatient hospital care, skilled nursing care and other services. Part B is paid for by monthly premiums of those who are enrolled and from general revenues. It helps pay for such items as doctors' fees, outpatient hospital visits and other medical services and supplies.

Most people have both parts of Medicare. If you have questions about this coverage, you can contact Medicare toll-free at 1-800-MEDICARE (1-800-633-4227) to speak to a Medicare Customer Service Representative. TTY users should call 1-877-486-2048.

Medicare added access to prescription drug coverage as of January 1, 2006. For more information, we recommend that you read Medicare's Prescription Drug Coverage page. People with limited income and resources may qualify for help with prescription drug plan costs.

SSI coverage is not earned.

SSI makes monthly payments to people who are 65 or older, blind, or disabled if they have a low income and few assets. Children as well as adults may qualify for SSI disability payments.

The federal government pays a basic rate and some states add money to that amount. Check with your local Social Security office for the SSI rates in your state.

SSI benefits are not paid from Social Security trust funds and are not based on past earnings. Instead, SSI benefits are financed by general tax revenues and assure a minimum monthly income for elderly and disabled persons.

To get SSI, you must be 65 or older or be disabled.

Children as well as adults qualify for SSI disability payments. As its name implies, Supplemental Security Income "supplements" your income up to various levels--depending on where you live.

Being eligible for SSI means you receive a monthly benefit and, depending on the state where you live, the following benefits and services:

• Medicaid
• Medicare premiums are paid (all states)
• food stamps and
• other assistance.

Additional information on SSI eligibility requirements can be found in:

• You May Be Able To Get Supplemental Security Income (SSI) (SSA Publication No. 05-11069) and

• The "Who is eligible for SSI?" section of A Guide To Supplemental Security Income (SSI) For Groups And Organizations (SSA Publication No. 05-11015).