A 30% coinsurance means you pay 30% of the allowed cost for a covered medical service, and your insurance company pays the remaining 70%. This cost-sharing only kicks in after you’ve met your annual deductible, and it continues until you hit your plan’s out-of-pocket maximum for the year.
How 30% Coinsurance Works in Practice
Coinsurance is always calculated on the “allowed amount,” which is the price your insurance company has negotiated with the provider for a given service. If you have 30% coinsurance and receive a treatment with an allowed amount of $1,000, you owe $300 and your insurer covers $700. For a $5,000 surgery, your share would be $1,500.
The key detail many people miss: coinsurance doesn’t apply to every dollar you spend. It only starts after you’ve paid your full annual deductible. So if your deductible is $2,000, you’re paying 100% of covered costs until you’ve spent that $2,000. After that threshold, your 30/70 split begins.
The sequence looks like this for a plan year:
- First: You pay the full allowed amount for services until your deductible is met.
- Then: You pay 30% coinsurance on each covered service; your insurer pays 70%.
- Finally: Once your total spending (deductible plus coinsurance plus copays) reaches your out-of-pocket maximum, your insurer covers 100% of covered care for the rest of the year.
Where 30% Coinsurance Is Common
On the ACA Marketplace, 30% coinsurance aligns with Silver-tier plans, where the plan covers roughly 70% of costs and you cover 30%. Bronze plans have you paying even more (around 40%), while Gold and Platinum plans reduce your share to about 20% and 10%, respectively. Silver plans tend to have moderate deductibles and are the most popular tier for people who qualify for cost-sharing reductions.
A 30% rate also frequently shows up as the out-of-network coinsurance on employer-sponsored plans. Many workplace plans charge a low coinsurance (like 10%) or a flat copay for in-network care, then jump to 30% coinsurance for out-of-network providers. In one typical example from a state employee plan, an in-network specialist visit costs a $25 copay, while the same visit out-of-network costs 30% of the bill after the deductible. That difference adds up fast for expensive procedures.
Medicare Part B, by comparison, uses a standard 20% coinsurance for most outpatient services. So 30% is higher than what Medicare beneficiaries pay, but lower than what you’d owe on a Bronze-level Marketplace plan.
Coinsurance vs. Copays
A copay is a flat fee: $30 for a doctor visit, $15 for a generic prescription. You know the number before you walk in. Coinsurance is a percentage, so your actual cost depends on how expensive the service is. A 30% coinsurance on a $200 lab panel is $60, but 30% on a $20,000 hospital stay is $6,000.
Plans often use copays for routine, predictable services (primary care visits, prescriptions) and coinsurance for bigger-ticket items like surgeries, imaging, or hospital stays. Some plans blend both. You might pay a $50 copay to see a specialist but 30% coinsurance for the MRI they order.
Your Out-of-Pocket Maximum Caps the Damage
Thirty percent of a major medical bill can be a serious number. A $50,000 hospitalization at 30% coinsurance would theoretically cost you $15,000. In practice, you’re protected by your plan’s out-of-pocket maximum, which is the most you can spend on covered in-network care in a single year. Once your deductible payments, coinsurance, and copays add up to that limit, your insurer pays 100% for the rest of the plan year.
For 2026 Marketplace plans, the out-of-pocket maximum can’t exceed $10,600 for an individual or $21,200 for a family. Your specific plan’s limit may be lower than that ceiling. This is the single most important number to check when you’re evaluating a plan with 30% coinsurance, because it determines your true worst-case scenario in a high-cost year.
What 30% Coinsurance Actually Costs You
The real financial impact depends on what kind of care you use. For someone who rarely sees a doctor beyond an annual checkup (which is covered at 100% with no coinsurance for preventive care), the 30% rate may never matter. For someone managing a chronic condition or facing a planned surgery, it matters a lot.
Consider a year where you need $15,000 in medical care after meeting a $2,000 deductible. At 30% coinsurance, your share of that $15,000 is $4,500, bringing your total out-of-pocket spending to $6,500. If your plan’s out-of-pocket maximum is $8,000, you’d pay the full $6,500. But if the bills kept climbing, you’d stop at $8,000 no matter what.
Plans with higher coinsurance rates like 30% typically come with lower monthly premiums. That tradeoff works well if you’re generally healthy and want to minimize what you pay each month. It’s a riskier bet if you expect significant medical expenses, since you’re trading lower premiums for higher costs at the point of care.