What Is Coinsurance in Health Insurance? A Plain-English 2026 Guide

Coinsurance in health insurance is the percentage of covered medical costs you pay after meeting your annual deductible. The most common split is 80/20 — your insurer pays 80%, you pay 20%. If a covered procedure costs $5,000 and you’ve already met your deductible, you owe $1,000 (20%) and your insurer covers $4,000 (80%). Your out-of-pocket maximum protects you from unlimited liability — in 2026, the ACA maximum is $9,200 for individuals. After hitting this maximum, your insurer covers 100% of remaining covered in-network costs for the year.

After Maria’s knee surgery, she received a bill for $3,200 from her surgeon and a separate bill for $1,800 from the hospital. She had met her $2,000 deductible earlier that year. She assumed the surgery would be fully covered. It wasn’t. Her plan had 20% coinsurance — meaning she owed 20% of all covered costs above her deductible. Her 20%: $1,000 total. She hadn’t budgeted for it. Her out-of-pocket maximum protected her from owing more beyond that, but the $1,000 was a genuine surprise.

What is coinsurance in health insurance? Coinsurance is the percentage of covered medical costs you pay after meeting your deductible — shared between you and your insurer. If your plan has 20% coinsurance (the most common level in the USA), you pay 20% of every covered medical bill after your deductible is met; your insurer pays 80%. This continues until you reach your out-of-pocket maximum.

This guide explains exactly how coinsurance works in 2026, how it differs from a deductible and a copay, what the most common coinsurance levels mean in practice, and how your out-of-pocket maximum limits total exposure — with real calculations and worked examples.

What Is Coinsurance in Health Insurance? Quick Summary

Feature	Details
Definition	The percentage of covered costs you pay after meeting your annual deductible
Most common levels	20% coinsurance (Gold plan, USA); 30% (Silver); 40% (Bronze)
When does it apply?	After you have met your annual deductible in full — coinsurance applies to all subsequent covered costs
What happens at the out-of-pocket max?	You pay 0% — insurer covers 100% of remaining covered in-network costs for the rest of the year
2026 ACA out-of-pocket maximum	$9,200 individual / $18,400 family
Coinsurance vs copay	Copay: fixed dollar amount per visit (e.g. $30 for a GP visit). Coinsurance: percentage of total cost.
Coinsurance vs deductible	Deductible: you pay 100% until you hit this amount. Coinsurance: you pay a % after hitting the deductible.
UK equivalent	Coinsurance doesn’t apply to NHS (free at point of use). In UK private medical insurance, excess is the equivalent of a deductible; most UK PMI policies don’t use coinsurance in the same way.

What Is Coinsurance in Health Insurance?

Think of coinsurance as a cost-sharing rule that applies once you’ve crossed the deductible finish line. Before the finish line: you pay 100%. After the finish line: you and your insurer share costs according to the coinsurance split. When you cross the out-of-pocket maximum: your insurer pays 100%.

Coinsurance is one of three cost-sharing mechanisms in US health insurance: the deductible (what you pay before insurance contributes), coinsurance (the percentage split after the deductible), and the copay (a fixed amount for specific services like a GP visit). Most plans use a combination of all three. Many plans have $0 coinsurance for in-network preventive care, even before meeting the deductible.

Why it exists: Coinsurance keeps policyholders financially engaged in the cost of their healthcare after the deductible. It discourages unnecessary medical spending by ensuring you still bear some portion of each additional cost, even after the deductible is met. This cost-sharing mechanism helps keep premiums lower than if the insurer covered 100% of all costs after the deductible.

How Coinsurance Works: Step by Step with Real Numbers

Scenario: Gold plan with $1,500 deductible, 20% coinsurance, $6,500 remaining out-of-pocket maximum after deductible (total max: $8,000). Maria has a knee surgery costing $16,000.

1. Step 1: You pay your full deductible. Maria has already paid $1,500 this year in doctor visits and prescriptions — her deductible is met.
2. Step 2: Coinsurance begins. Maria’s knee surgery: $16,000 allowed amount (in-network agreed rate between insurer and hospital). After deductible already met, Maria owes 20% of $16,000 = $3,200. Insurer pays 80% = $12,800.
3. Step 3: Check the out-of-pocket maximum. Maria’s out-of-pocket maximum is $8,000 ($1,500 deductible + $6,500 coinsurance maximum). Her total so far: $1,500 (deductible) + $3,200 (20% coinsurance) = $4,700. She has $3,300 remaining before hitting her maximum.
4. Step 4: Subsequent costs after hitting the maximum. If Maria has additional medical expenses later that year, she owes 0% — the insurer covers 100% of remaining covered in-network costs until January 1, when everything resets.

Situation	Amount	Who Pays?
Surgery cost (in-network allowed amount)	$16,000	—
Maria’s deductible (already met earlier in year)	$1,500	Maria (already paid)
Maria’s coinsurance on surgery (20% of $16,000)	$3,200	Maria
Insurer’s share of surgery (80% of $16,000)	$12,800	Insurer
Maria’s total out-of-pocket so far this year	$4,700	Maria
Maria’s remaining exposure before out-of-pocket max	$3,300	Maria — until she hits $8,000 total
After out-of-pocket maximum hit	$0	Insurer pays 100%

Coinsurance Rates by Metal Tier — USA ACA Plans 2026

Metal Tier	Typical Coinsurance Rate	You Pay (per $1,000 of covered costs after deductible)	Insurer Pays
Bronze	40%	$400	$600
Silver (standard)	30%	$300	$700
Silver (with CSR, 250% FPL)	~15–20%	$150–$200	$800–$850
Gold	20%	$200	$800
Platinum	10%	$100	$900
Employer plan (average 2026)	20%	$200	$800

Coinsurance vs Copay vs Deductible: The Complete Comparison

Term	Definition	When It Applies	Example
Deductible	Fixed annual amount you pay 100% before insurance contributes	First medical expenses of each calendar year	You pay first $2,000 of medical costs each year
Coinsurance	Percentage of costs shared between you and insurer after deductible	After deductible is met, on all covered services	After deductible: you pay 20%, insurer pays 80%
Copay	Fixed dollar amount for a specific service, regardless of total cost	Often applies even before deductible for certain services (e.g. primary care, prescriptions)	$30 for every primary care visit; $50 for every specialist visit
Out-of-pocket maximum	The total annual cap on your spending (deductible + coinsurance + copays)	After hitting this total, insurer covers 100% for the rest of the year	$9,200 ACA individual maximum in 2026

 

💡 TIP: Your Deductible Counts Toward Your Out-of-Pocket Maximum A common source of confusion: the deductible is part of your out-of-pocket maximum — it counts toward it. If your out-of-pocket maximum is $8,000 and your deductible is $2,000, you only need to spend $6,000 more in coinsurance and copays to hit your maximum. Your insurer then covers 100% for the rest of the year. Many people mistakenly believe they need to spend the full out-of-pocket maximum AFTER the deductible — this would mean paying deductible + maximum, which is not how it works.

Does Coinsurance Apply to All Medical Services?

No. Many services have specific rules regardless of coinsurance:

• Preventive care (in-network): covered at 100% on all ACA plans — no deductible, no coinsurance, no copay. Includes annual physicals, immunisations, and recommended screenings.
• Prescriptions: may have separate coinsurance tiers (generic vs brand vs specialty) that differ from medical coinsurance rates.
• Emergency care: emergency room visits usually have a copay or deductible requirement even with coinsurance, and out-of-network emergency care may be subject to different coinsurance rates.
• Mental health and substance use: ACA requires parity with medical/surgical coinsurance — mental health services cannot be subject to higher coinsurance than equivalent physical health services.
• Dental and vision: typically separate plans with their own coinsurance structures — not part of medical plan coinsurance.

4 Real Coinsurance Scenarios

Scenario 1: Maria — Knee Surgery, 20% Coinsurance

Deductible met. Surgery: $16,000. Maria pays: $3,200 (20%). Insurer pays: $12,800 (80%). Out-of-pocket max: $8,000. Maria has already paid $1,500 deductible. She needs to pay a further $3,200 in coinsurance before hitting her $6,500 coinsurance cap. This surgery nearly uses her full out-of-pocket maximum in one event.

Scenario 2: Bronze Plan Holder — High Coinsurance Risk

David chose a Bronze plan for the low premium ($573/month). He has 40% coinsurance. He is diagnosed with a condition requiring $30,000 in treatment. He has met his $7,000 deductible. His 40% coinsurance: $30,000 × 40% = $12,000 — but his out-of-pocket maximum is $9,200. His actual maximum exposure: $9,200 total for the year. The ACA out-of-pocket maximum protects Bronze plan holders from unlimited coinsurance liability.

Scenario 3: CSR Silver Plan — Dramatically Reduced Coinsurance

Sandra earns $28,000 (175% FPL) and has a CSR Silver plan. Her standard Silver coinsurance of 30% is reduced to 15% with her CSR benefit. On the same $30,000 treatment: standard Silver = $9,000 in coinsurance. CSR Silver = $4,500. The CSR subsidy effectively doubles the value of every dollar of coverage she receives.

Scenario 4: Employer Plan — Most Common Coinsurance Structure

James has an employer-sponsored PPO with 20% coinsurance after a $1,750 individual deductible. His knee surgery costs $12,000. He’s met his deductible. He pays: $12,000 × 20% = $2,400. His employer plan out-of-pocket maximum: $8,150 (2026 maximum for employer plans). He’s paid $1,750 deductible + $2,400 coinsurance = $4,150 total. Still well below his maximum — all further costs this year will continue at 20% until he hits $8,150 total.

Frequently Asked Questions

What is coinsurance in health insurance?

Coinsurance in health insurance is the percentage of covered medical costs you pay after meeting your annual deductible, shared between you and your insurer. The most common split is 80/20 — you pay 20%, your insurer pays 80%. This continues until you reach your annual out-of-pocket maximum, after which the insurer covers 100% of remaining covered in-network costs for the year. The 2026 ACA out-of-pocket maximum is $9,200 for individuals.

How is coinsurance different from a deductible?

A deductible is the fixed annual amount you pay 100% before your insurance contributes anything (for most services). Coinsurance is the percentage split that applies after your deductible is met — you pay a set percentage of each covered service and your insurer pays the rest. Think of it this way: deductible = pay 100% until you hit the amount; coinsurance = pay a % once you’ve crossed the deductible threshold.

What is the 80/20 coinsurance rule?

The 80/20 coinsurance rule is the most common coinsurance split in US health insurance, particularly Gold-tier ACA plans and most employer-sponsored plans. Under 80/20 coinsurance, your insurer pays 80% of covered medical costs after your deductible, and you pay 20%. On a $5,000 covered medical bill after the deductible: you pay $1,000, your insurer pays $4,000.

Do I pay coinsurance and a copay?

It depends on the plan. Some plans use copays (fixed dollar amounts) for specific services like primary care ($30) and specialists ($50), and coinsurance (percentage) for hospital stays and procedures. Some plans use only coinsurance, some only copays, and many use both depending on the type of service. Always check your plan’s Summary of Benefits and Coverage (SBC) to understand which cost-sharing mechanism applies to each category of service.

Key Takeaways

• Coinsurance is the percentage of covered medical costs you pay after meeting your annual deductible. The 80/20 split is most common — you pay 20%, your insurer pays 80%.
• Coinsurance applies after the deductible is met. Before the deductible: you pay 100%. After: you pay the coinsurance percentage. After the out-of-pocket maximum: insurer pays 100%.
• The 2026 ACA out-of-pocket maximum is $9,200 individual — this includes your deductible, coinsurance, and copays. Once hit, the insurer covers 100% for the rest of the year.
• Deductible ≠ out-of-pocket maximum. Your deductible counts toward your maximum. If your max is $8,000 and your deductible is $2,000, you pay only $6,000 more in coinsurance/copays before hitting the maximum.
• CSR Silver plans can reduce your coinsurance from 30% (standard Silver) to as low as 10–15% at qualifying income levels — dramatically improving the value of coverage.

For the full explanation of how deductibles work alongside coinsurance, see our what is deductible insurance] guide. For a complete overview of how health insurance works, our what is health insurance article covers all the fundamentals.

📋 Disclaimer This article is for informational purposes only. Always consult a licensed insurance professional before making coverage decisions. Trust My Policy does not sell insurance products or represent any insurer.