After Monday, many Americans will start paying a lot more for health insurance when their 15-month federal Cobra premium subsidy runs out.

These are the people who started receiving the premium in March 2009, when it first became available to laid-off workers who were eligible to remain in their group health plan, under either the federal law known as Cobra or a state version.

Former employees receiving health coverage under Cobra normally pay 100 percent of the insurance premium, but those getting the subsidy pay only 35 percent and the government pays 65 percent.

The subsidy originally was supposed to last nine months, but it was later extended to 15 months. Congress does not seem willing to extend the coverage period past 15 months, although it is considering extending the eligibility period, which also ends Monday.

The American Jobs and Closing Tax Loopholes Act would extend the deadline to qualify for the subsidy until the end of this year. If an extension is not passed, workers who get laid off after Monday will receive no Cobra subsidy.

Those receiving the subsidy today could continue getting it until their 15 months run out, but the bill would not extend the coverage period beyond 15 months.

If you are about to lose the subsidy, or Cobra coverage entirely, it's crucial to plan ahead.

Federal Cobra applies to employers with 20 or more workers. It lets workers who quit or lose their jobs stay in the group health plan, usually for up to 18 months. But employers can charge former workers the full health insurance premium, plus a 2 percent administrative fee.

Many states have similar laws that cover employers with fewer than 20 workers. California's version, Cal-Cobra, lets some people stay in their old health plan for up to 36 months.

Workers who were involuntarily terminated after Sept. 1, 2008, and eligible under federal or state Cobra could receive the federal subsidy, starting in March 2009.

People who were terminated after Sept. 1, 2008, and initially declined Cobra coverage were allowed to rejoin their old health plan and begin receiving the subsidy starting in March 2009. This large group of people will lose the subsidy at the end of May.

After May, these people can stay in their group plans, and pay the full premium, until their 18- or 36-month Cobra eligibility ends.

Cal-Cobra

If you live in California and exhaust 18 months of federal Cobra, you might be able to stay in your plan for 18 more months under Cal-Cobra, for a total of 36 months.

You generally can not get this extended coverage if your former employer is self-insured - and many big ones are, even if they hire an insurance company to administer the health plan. Also, if your insurance policy was issued in a state other than California, you will not get the extra 18 months of coverage under Cal-Cobra, although you might get additional months under the other state's Cobra law.

For help, call the California Department of Insurance at (800) 927-4357 or the Department of Managed Health Care at (888) 466-2219 or visit their Web sites at links.sfgate.com/ZJSS or links.sfgate.com/ZJST.

Consumer tips

If you are about to lose your Cobra subsidy, here are some tips.

-- If you are healthy, an individual or family plan will usually be cheaper than paying 100 percent of your Cobra premium. Shop for a plan at sites such as Ehealthinsurance.com or call an insurance broker. Do not drop your Cobra coverage until you are approved for a new plan, even if you have to pay the full Cobra premium for an extra month.

-- If you have a pre-existing condition, it will usually be cheaper to stay in your group health plan and pay the entire premium until your Cobra or Cal-Cobra eligibility ends, then switch to a HIPAA plan, says Carrie McLean, a consumer specialist with Ehealthinsurance.

HIPAA stands for a federal law that lets eligible people who have recently lost group health coverage purchase an individual or family plan, even if they have pre-existing conditions. After you lose group coverage (including Cobra or Cal-Cobra if you are eligible) you have only 63 days to apply for a HIPAA policy. All carriers that sell individual health care policies must offer two popular plans to HIPAA-eligible individuals. Start with your existing carrier, but shop around, McLean says.

HIPAA policies can be quite expensive, but they are still better than going without coverage or going into a state high-risk pool, which provides limited coverage for people who have been rejected for insurance. For information on California's pool, go to www.mrmib.ca.gov or call (800) 289-6574.

-- Investigate public options. If your income is low and you meet other requirements, you could qualify for Medi-Cal, the state's Medicaid program. Medi-Cal is free or cheap, depending on your income and county.

"It's comprehensive medical coverage, and if you have a pre-existing condition, you can't get turned down. The hardest part is signing up and getting enrolled. There are a lot of barriers," says Ankeny Minoux, president of the nonprofit Foundation for Health Coverage Education.

To learn more about public programs in every state and take an eligibility quiz, go to the foundation's Web site at www.coverageforall.org or call (800) 234-1317.

Some children might qualify for coverage under California's Healthy Families program, which has slightly higher income limits than Medi-Cal. See www.healthyfamilies.ca.gov or call (800) 880-5305.

-- Mix and match your options. Minoux says she just helped a family of four that is losing its Cobra subsidy. Rather than pay 100 percent of the Cobra premium for family coverage, one parent - who is healthy - got an individual policy. The other parent, who had a pre-existing condition, will remain on Cobra as a single person until it runs out and then get a HIPAA policy. The two children qualified for Healthy Families. The total cost is less than what the family would pay to stay on Cobra as a family.

Net Worth runs Tuesdays, Thursdays and Sundays. E-mail Kathleen Pender at kpender@sfchronicle.com.

This article appeared on page D - 1 of the San Francisco Chronicle