Even if you have health insurance, you could wind up paying large sums out-of-pocket for care should you make mistakes. How to minimize costly errors:Get pre-authorization.
If you’re required to get an authorization from your plan prior to treatment, be sure you do so. Don’t assume the plan will pay simply because the treatment was medically necessary. Double-check with the treating doctor to make sure that he or she has the authorization in hand.

Seek a referral.
Know whether you have to seek a referral from your primary-care doctor before visiting a specialist. Even if you get the proper referral, any treatments that arise from that visit may still require preauthorization.

Know the limits.
Your plan’s benefits and payments may have limitations. For example, if your plan pays $50 for a visit and you consult a more-expensive doctor who charges $85, you must pay the $35 difference.

Know the deadlines.
If you want to dispute a denial of your claim or the insurer payment, you typically have up to six months. Know the cut-off date—otherwise, you could lose an appeal by missing a deadline.

Know the deductibles.
Understand how much your deductible is and what it applies to. For example, a preventive checkup might be covered even if you haven’t met your deductible, but a subsequent treatment that the doctor prescribes during that visit might not be. Or your plan may cover a visit but not a procedure performed on the same day.

Price the drugs.
To avoid being charged for lots of expensive brand-name prescription drugs, ask your doctor to prescribe an equivalent generic or a less-expensive medication whenever possible.