The government never makes anything easy, but you may be pleasantly surprised that the requirements for Medicare eligibility are fairly simple math.

If you’ve worked for at least 10 years and are 65 years of age, you’re eligible for Medicare benefits; and if you’ve never worked but your spouse has, you can qualify based on that criterion. Once you’ve signed up for Medicare, you can choose your coverage options, including Medicare advantage enrollment.

Medicare was originally set up in 1965 by President Johnson as part of his social programs generally referred to as “the Great Society.” Medicare is funded through payroll taxes, which you’ve most likely seen deducted from your paycheck over the years. Johnson’s “War on Poverty” was propelled by the 44% of seniors in the U.S. who were uninsured at the time and often bankrupted by the cost of healthcare. With advances in medicine, today’s seniors are living longer, healthier lives, and health insurance plays a major role in that statistic.

Not just U.S. citizens, but legal permanent residents are eligible for Medicare coverage. If you or your spouse worked in the government and didn’t have Social Security withheld, you are still eligible for Medicare since it was deducted from payroll taxes. Certain medical conditions also entitle you to Medicare before your 65th birthday, such as ALS (Lou Gehrig’s disease), chronic kidney disease that requires transplant or dialysis or if you’ve been on disability for at least two years.

If you’re still not sure when or if you qualify for Medicare, the government offers a handy online tool. All you need to do is type in your date of birth and answer two qualifying questions to find the exact date of your eligibility.

Medicare coverage comes in four parts:

• Part A is considered catastrophic coverage for hospital stays and short-term care in skilled nursing facilities. If you’re still working, you won’t need to pay a premium for this coverage since it’s paid directly from your paycheck.
• Part B is outpatient medical coverage, which generally comes along with Part A and covers doctor’s visits, as well as office procedures and medical equipment. This typically involves a monthly premium of,just under $100.
• Part C is where Medicare advantage enrollment comes in. This type of coverage is similar to that of an HMO or PPO where you pick an in-plan provider. The coverage offered through Medicare advantage enrollment may provide more services than you’d get with standard Medicare, such as vision, dental and/or chiropractic.
• Part D is prescription drug coverage, which also may be offered if you opt for Medicare advantage enrollment.

Once you’ve determined that you’ve met the requirements for Medicare eligibility, you’ll need to sign up. If you’re already receiving Social Security and meet the age requirement, you’ll have a card sent to you automatically, and your coverage starts the month you turn 65. Otherwise, you have a seven-month window in which to sign up: three months before your birthday month to three months after your birthday month. I

If you miss the deadline, there’s a 10% penalty for Part B coverage. Call Social Security at 1-800-772-1213 to apply for Medicare or you can do it online.