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What Is Coinsurance?

what is coinsurance? It is the percentage of an allowed charge a member pays for a covered service under the plan’s cost-sharing rules.

By the Health Insurance Match Editorial Team · Last reviewed July 14, 2026

How Coinsurance Is Calculated

If a plan uses coinsurance, the member pays a stated percentage and the plan pays its stated share of the allowed amount after any applicable deductible. The billed charge and allowed amount may differ.

Network and Authorization Matter

In-network providers generally accept contracted allowed amounts. Out-of-network services may use different coinsurance, deductibles, allowed amounts, and balance-billing rules. Prior authorization can also affect coverage.

Planning for Percentage-Based Costs

Coinsurance can make expensive services less predictable than a fixed copayment. Compare the percentage together with the deductible, likely allowed charges, and out-of-pocket maximum.

Key Points to Compare

Item Why it matters
20% coinsurance Member pays 20% of the applicable allowed amount
In-network Contracted rate and in-network cost sharing apply
Out-of-network Different percentage and additional exposure may apply
Out-of-pocket maximum Eligible covered spending may count toward the annual limit

Practical Next Steps

  1. Confirm your enrollment opportunity and coverage source.
  2. List providers, prescriptions, and expected services.
  3. Compare total cost, network access, and plan documents.
  4. Use current official sources for eligibility and deadlines.

Learn how health insurance works, browse coverage by state, or use our PPO vs. HMO comparison.

Frequently Asked Questions

Is coinsurance the same as a copay?

No. Coinsurance is a percentage; a copayment is usually a fixed amount.

Does coinsurance apply before the deductible?

It depends on the plan and service.

Can I estimate coinsurance before care?

Ask the provider and plan for an estimate, but actual claims and services may differ.

Official Sources

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HealthInsuranceMatch.com is an independent informational resource, not a government website, Marketplace, insurer, or guarantee of eligibility, savings, price, or coverage. Verify current rules and plan documents.