How Deductibles and Coinsurance Split Your Health Care Bill

In U.S. health insurance, your deductible is the amount you pay before the plan starts sharing costs for services subject to that deductible. Coinsurance is your percentage of covered costs after you meet it. Meeting the deductible does not necessarily mean your next bill is free. HealthCare.gov explains this sequence.

The practical question is not just “What is my deductible?” It is “How much deductible remains, what percentage do I owe afterward, and when does that cost sharing stop?”

Deductible vs. coinsurance

• Deductible: A dollar amount you must satisfy over a coverage period, usually one year. If your deductible is $2,000 and you have already satisfied $1,500, you have $500 left—not another $2,000 on each bill.
• Coinsurance: A percentage, such as 20%, applied to the covered amount after the applicable deductible. If your share is 20%, the plan pays the other 80%, until you reach the applicable out-of-pocket limit.
• Copayment: A fixed dollar charge, such as $30 for a covered visit, rather than a percentage. A service may have a copay instead of coinsurance; check its benefit terms.

These are separate cost-sharing mechanisms, as defined in the CMS guide to health insurance terms.

For covered in-network care, calculate coinsurance using the plan’s allowed amount, often its negotiated rate—not automatically the provider’s original charge. CMS also notes that an in-network provider may not balance bill you for covered services. Out-of-network billing can work differently.

Example: one bill crosses the deductible

Hypothetical plan and claim:

• Annual deductible: $2,000
• Deductible already satisfied: $1,500
• Your coinsurance: 20% after the deductible
• In-network out-of-pocket limit: $5,000
• Allowed amount for covered treatment: $5,000
• Exclusion: This example plan does not cover elective cosmetic treatment.

Assume the treatment is covered, subject to the deductible, and meets the plan’s requirements. Also assume your only earlier cost sharing was the $1,500 applied to the deductible.

Calculation	Amount
Remaining deductible you pay	$500
Covered amount left after deductible: $5,000 − $500	$4,500
Your coinsurance: 20% × $4,500	$900
Your share of this claim: $500 + $900	$1,400
Plan’s share: 80% × $4,500	$3,600

You do not pay the remaining $500 deductible plus 20% of the entire $5,000. Coinsurance applies to the $4,500 left after the deductible in this example. This follows HealthCare.gov’s deductible-plus-coinsurance calculation.

If the deductible had already been fully satisfied, your share would instead be $1,000: 20% of $5,000, assuming you had enough room below the out-of-pocket limit.

The out-of-pocket limit stops eligible cost sharing

The deductible is not your annual spending ceiling. For Marketplace plans, the out-of-pocket maximum includes deductibles, copayments and coinsurance for covered in-network care. Once you reach it, the plan pays 100% of covered in-network benefits for the rest of the plan year. HealthCare.gov describes what counts toward this limit.

In the example, your eligible spending reaches $2,900: the earlier $1,500 plus this claim’s $1,400. That leaves $2,100 before the hypothetical $5,000 limit.

The limit does not cap every health expense. Premiums, noncovered services and balance-billed amounts do not count toward it. Out-of-network care generally does not count toward the in-network limit either. If you separately buy treatment excluded under the hypothetical plan, that expense does not become covered because you met the deductible or maximum.

Check the benefit before applying the formula

Not every service follows “deductible, then coinsurance.” Many plans cover some services before the deductible; prescription drugs may have a separate deductible, and family plans may have individual and family thresholds. Check these deductible exceptions. Certain preventive services are generally covered without cost sharing when provided in-network, though $0 is not guaranteed in every case. See the preventive-care rules.

Before scheduling care or comparing quotes, get the plan’s Summary of Benefits and Coverage and check:

1. Whether the service is covered and which network rules apply.
2. Whether its deductible applies.
3. Whether you owe a copay, coinsurance, or separate charges for different parts of the care.
4. The out-of-pocket limit and any authorization requirements or exclusions.

The SBC summarizes benefits; it does not show your current spending balances. Ask the insurer how much deductible and out-of-pocket limit remains, and consult the full plan documents for detailed restrictions.

After a claim, compare the provider’s bill with your Explanation of Benefits (EOB). The EOB shows the charges and how much you and the plan owe; it is not itself a bill. If the calculation differs from your estimate, ask the insurer which allowed amount, deductible balance and benefit rule it used.