Coinsurance Calculator

How it is calculated

The tool treats the bill as one covered claim. First you pay the deductible, up to the size of the bill: deductible paid = min(bill, deductible). The rest, bill − deductible (never below zero), is shared, and you pay your coinsurance percentage of it. Your cost is min(deductible paid + (bill − deductible) × rate ÷ 100, out-of-pocket max), so the maximum caps it, and the insurer pays bill − your cost. The coinsurance field is your share in percent (0 to 100; anything above 100 gives no result), so an 80/20 plan is entered as 20. The bill must be above zero. It also reports whether the cap was reached. The calculator assumes the full deductible is still unmet and the out-of-pocket max untouched at the start of this bill, so earlier claims this year are not tracked. Amounts are in dollars; copays, premiums and out-of-network rules are left out.

Common mistakes

• Entering the insurer's share. An 80/20 plan means you pay 20 %, so type 20; typing 80 would badly overstate what you owe.
• Forgetting that the deductible comes first. Coinsurance applies only to the amount above the deductible, so a $1,000 bill with a $1,500 deductible costs you the whole $1,000.
• Entering a family out-of-pocket limit, or a huge number, as the maximum. The cap only matters if it is realistic for your own plan; a very large value means it will never apply.
• Ignoring what you already paid this year. The tool starts the deductible and cap from scratch for this bill, so if you have already met part of them, your real cost is lower.
• Assuming everything on the bill is covered. Out-of-network charges and non-covered items are billed differently, so the result applies only to covered costs.