Your health plan has four dollar figures on it, and they don't work the same way. People pick a plan on the premium, because the premium is the one number that's easy to compare. Then a bill shows up in March that they weren't expecting.
The deductible is what you pay before the plan starts sharing the cost. A $3,000 deductible means the first $3,000 of covered care in the year comes out of your pocket. Two exceptions matter here. Preventive care, meaning the yearly physical, the screenings, and the vaccines, is covered at no cost before the deductible on any plan that follows the Affordable Care Act. And a lot of plans let office visits and generic drugs run on a copay from day one, so you don't have to clear the deductible first.
A copay is a flat amount. Thirty dollars for the doctor, sixty for the specialist, and the number is printed on your card. Coinsurance is a percentage, and it starts after you've met the deductible. Coinsurance of 20% on a $10,000 procedure means $2,000 from you and $8,000 from the plan. Copays are easy to plan for. Coinsurance is what produces the frightening bill, because 20% of a hospital stay is real money.
The out-of-pocket maximum is the ceiling over all of it. Your deductible, your copays, and your coinsurance all count toward that ceiling. Once you hit it, the plan pays 100% of covered in-network care for the rest of the year. Premiums do not count toward it. Neither does out-of-network care on most plans, and neither does anything the plan doesn't cover at all. For 2026 the legal ceiling is $10,600 for one person and $21,200 for a family, and most employer plans sit well under it.
Family plans hide a difference that costs real money. An embedded deductible gives each person their own deductible inside the family one, so one sick family member hits theirs and starts getting coverage. An aggregate deductible means nothing pays until the whole family total is met, so one sick person pays the entire family deductible alone. The plan document says which one you have. Ask HR if it isn't obvious, and ask before you enroll.
So compare two plans this way. Add up a year of premiums plus the out-of-pocket maximum, which is your worst case. Then add up a year of premiums plus what you expect to actually use, which is your likely case. A high deductible plan with a $6,000 premium advantage wins the terrible year and the healthy year both. The low deductible plan comes out ahead in the middle, when you use a fair amount of care but not a catastrophic amount.
If the high deductible plan qualifies as an HDHP, which means a high deductible health plan under the IRS rules, it comes with access to an HSA. That shifts the math again in a way most comparison spreadsheets leave out. What that account does is in the health account that gets three tax breaks.