You might think that you don’t have to worry about paying for medical care if you have health insurance. But you would be wrong. The results of a recent Consumer Reports’ survey shows the depth of jitters even for those lucky enough to have insurance through their jobs and families.

In a nationally representative survey of more than 2,900 working-age adults, CR found that 29 percent of those who had health insurance through their jobs or families were “underinsured,” with coverage so meager that they often postponed medical care because of costs. Some 43 percent of insured respondents, moreover, said they were “somewhat” to “completely” unprepared to cope with a costly medical emergency during the coming year.

It’s no wonder, then, that some insured survey respondents said they ran up large debts, dug deep into their savings or deferred home and car maintenance to meet medical expenses, even those with insurance. If, like these underinsured Americans, you’re feeling the pinch from rising medical costs, taking these steps can help you make the most of your health plan:

• Know what you have. There is no such thing as a “standard” health plan. If you’re lucky, your employer or insurer will provide you with a handy list of features. If not, you’ll have to study your Summary Plan Description. Most critical: good hospitalization coverage, because hospital bills are by far the most expensive health care most people will ever use. CR has created a standardized form, available at www.consumerreports.org/health, to help you clarify your plan’s provisions.
• Sweat the details. Remember: Insurance isn’t for when you’re healthy – it’s for when you’re sick. Does your plan’s mental-health coverage include ample counseling visits, inpatient days and substance-abuse treatment? How many days of physical therapy are you allotted, in case you have a stroke? Good “durable medical equipment” coverage can make all the difference for someone who needs a breathing machine or a wheelchair.
• Do the math. Do a “worst case” calculation of your maximum annual costs. Here’s how: Add up the total annual cost of your premium, plus your plan’s annual out-of-pocket cap. If it’s too high, you might want to trade higher premiums for a lower out-of-pocket limit. If you have enough money saved up to cope with an occasional bad year, your trade-off might go the other way.
• Follow the rules. Every major carrier offers many plans, each with distinct rules and requirements. If you don’t follow them, it could cost you. For example, while an operation may be covered by your insurance, an attending physician may not be part of your health plan, leaving you paying for more than you expected.

  If you aren’t sure whether a particular doctor participates in your plan’s network, check not only with the insurance company but also with the doctor’s billing staff.

• Don’t get locked out. The 1996 federal Health Insurance Portability and Accountability Act protects people from losing coverage for pre-existing conditions when they switch jobs. Under HIPAA, insurers can’t deny you complete coverage as long as you switch from one plan to the next within 63 days (more in some states) and your earlier coverage lasted for at least a year.
• Understand COBRA. The 1986 federal Consolidated Omnibus Budget Reconciliation Act allows you to continue your group coverage after you leave your job – unless your group had fewer than 20 people in it. But you generally have to pay the entire premium, including the portion your employer used to pay. You usually can stay on COBRA for 18 months.
• Fight back. You are not at the mercy of your health plan’s decisions on coverage and payment. You have certain rights under state or federal law to appeal health-plan decisions that you think are wrong. For complete information, including a guide to state laws and procedures, consult “A Consumer Guide to Handling Disputes with Your Employer or Private Health Plan,” available online at www.consumerreports.org/health.