Health insurance cost-sharing involves multiple layers that determine your total annual medical expenses. Understanding how these components interact—premiums, deductibles, coinsurance, copays, and the out-of-pocket maximum—is essential for choosing the right plan and budgeting accurately.
Premiums: Your Baseline Recurring Cost
Premiums are the monthly amount you pay to maintain insurance coverage, regardless of whether you use any medical services. They are paid every month (or deducted from paychecks) and typically do not count toward your deductible or out-of-pocket maximum. Some rare plan designs may count premiums toward the OOP max, but this calculator treats premiums as a separate recurring baseline cost, which is the standard industry approach.
Premium amounts vary by plan type (HDHP, PPO, HMO), coverage tier (individual, individual+spouse, individual+children, family), and employer contribution. Marketplace plans show premiums before premium tax credits; employer plans show premiums after employer subsidies. Lower premiums usually mean higher deductibles and OOP maximums—this is the fundamental trade-off in plan selection.
Deductible: What You Pay Before Coinsurance Kicks In
The deductible is the amount you must pay out-of-pocket for covered services before your insurance begins paying its share through coinsurance. Once you meet the deductible, the insurance company starts sharing costs at the coinsurance rate (e.g., 80/20, where insurance pays 80% and you pay 20%).
Important exceptions: Some services bypass the deductible entirely:
- Preventive care: Annual physicals, vaccinations, cancer screenings, and wellness visits are covered at 100% with no deductible or copay (ACA requirement for in-network preventive services).
- Copay-only services: Primary care visits, specialist visits, urgent care, and emergency room visits may have a fixed copay instead of applying to the deductible, depending on plan rules. Use the calculator's "Copays apply before deductible" toggle to model this.
- Prescription drugs: Some plans have a separate Rx deductible; others apply drug costs to the medical deductible. Toggle "Separate Rx deductible" in the calculator to model your plan's structure.
Family plans have both individual and family deductibles. Once one family member meets the individual deductible, their services move to coinsurance. The family deductible is the maximum the entire family must pay before everyone moves to coinsurance—no single member can exceed the family deductible.
Coinsurance: Your Share After the Deductible
Coinsurance is the percentage you pay for covered services after meeting your deductible. Common coinsurance splits are 80/20 (insurance pays 80%, you pay 20%), 70/30, or 90/10. Coinsurance continues until you reach your out-of-pocket maximum, at which point the insurance covers 100% of remaining covered services for the rest of the year.
Example: You've met a $3,000 deductible and have 80/20 coinsurance. You undergo surgery with a $10,000 allowed amount. You pay 20% of $10,000 = $2,000 (coinsurance). This $2,000 accrues toward your out-of-pocket maximum. If this pushes you over the OOP max, you pay only enough to reach the cap, and insurance covers the rest at 100%.
Copays: Fixed Amounts for Specific Services
Copays (copayments) are fixed dollar amounts you pay for specific services, such as $25 for a primary care visit, $50 for a specialist, $100 for urgent care, or $250 for an ER visit. Copays may apply before you meet your deductible (bypassing the deductible) or after the deductible (in lieu of coinsurance for those services).
Whether copays count toward your deductible and/or out-of-pocket maximum depends on plan rules. Many plans apply copays directly to the OOP max but not the deductible. Use the calculator's toggles to model your specific plan:
- "Copays apply before deductible": If checked, copays are charged even before you meet the deductible.
- "Copays count toward deductible": If checked, copay amounts accrue to help you meet the deductible faster.
- "Copays count toward OOP": If checked, copays accrue toward the out-of-pocket maximum (common on most plans; unchecked on some HDHPs).
Prescription drug copays often work differently: they may have tiered copays (Tier 1 generics $10, Tier 2 preferred brand $40, Tier 3 non-preferred $80, Tier 4 specialty $200+) and may or may not apply to the medical deductible/OOP max depending on plan structure.
Out-of-Pocket Maximum: Your Annual Cap
The out-of-pocket maximum (OOP max) is the most you'll pay in cost-sharing (deductible + coinsurance + copays that count toward OOP) for covered in-network services in a calendar year. Once you reach this cap, the insurance covers 100% of remaining covered services for the rest of the year.
What counts toward the OOP max: Deductible payments, coinsurance, and copays (if plan rules include them). What does NOT count: Premiums, out-of-network charges exceeding allowed amounts, non-covered services (cosmetic procedures, experimental treatments), and balance billing from non-contracted providers.
ACA-compliant plans have federally mandated OOP max limits (2024: $9,450 individual / $18,900 family). Employer plans often set lower limits (e.g., $5,000 individual / $10,000 family). Family plans have both individual and family OOP maximums—once one person reaches the individual OOP max, their services are covered at 100%; once the family collectively reaches the family OOP max, everyone is covered at 100%.
Allowed Amount vs. Billed Amount
Your cost-sharing (deductible, coinsurance, copays) applies to the allowed amount, not the provider's billed charge. The allowed amount is the negotiated rate your insurance company has contracted with in-network providers. For example, a provider bills $10,000 for surgery, but the insurance's allowed amount is $6,000. Your coinsurance applies to the $6,000, not $10,000. The provider writes off the $4,000 difference—you never pay it.
Out-of-network care typically has:
- Higher allowed amounts (insurance's "reasonable and customary" rate, often 150-200% of in-network rates)
- Separate, higher deductibles and OOP maximums
- Balance billing risk: The provider can bill you for the difference between their charge and the insurance payment (outlawed for in-network emergency care under the No Surprises Act but still possible for non-emergency out-of-network care)
This calculator models in-network care by default. Toggle "Out-of-network coverage" to apply separate deductibles/OOP max and higher coinsurance percentages.
HSA & FSA Tax Savings
Health Savings Accounts (HSAs) and Flexible Spending Accounts (FSAs) allow you to pay for eligible medical expenses with pre-tax dollars, reducing your after-tax cost by your marginal tax rate.
HSA: Available only with High Deductible Health Plans (HDHPs). Contributions are tax-deductible (or pre-tax via payroll), grow tax-free, and withdrawals for qualified medical expenses are tax-free (triple tax advantage). 2024 contribution limits: $4,150 individual / $8,300 family (+$1,000 catch-up if 55+). Funds roll over year-to-year and can be invested for long-term growth—many use HSAs as a retirement savings vehicle for future medical expenses.
FSA: Available with most employer plans. Contributions are pre-tax via payroll, but funds are use-it-or-lose-it (some plans allow $610 rollover or 2.5-month grace period). 2024 limit: $3,200. FSAs cannot be invested and must be spent each year, making them best for predictable recurring expenses (prescriptions, orthodontia, glasses).
This calculator applies your marginal tax rate to eligible out-of-pocket expenses paid with HSA/FSA dollars, showing your after-tax cost. For example, if you're in the 24% bracket and spend $5,000 on medical care via HSA, your after-tax cost is $5,000 × (1 - 0.24) = $3,800 effective cost due to the tax savings.