What is the Medicare Part D donut hole?

The donut hole (coverage gap) was a stage where beneficiaries paid a much higher share of drug costs. It has been largely closed — beneficiaries pay 25% of drug costs in the gap, the same as the initial coverage stage. The IRA's $2,000 OOP cap further protects against high costs.

How does the $2,000 out-of-pocket cap work?

Under the capped Part D structure modeled on this page, total out-of-pocket costs for covered drugs stop at $2,000 for the year. Once you reach that amount, you pay nothing for covered drugs for the rest of the year. Plans must also offer a monthly payment option so you can spread those costs over time.

Do premiums count toward the out-of-pocket cap?

No. Monthly premiums are separate from the OOP cap. The cap only includes what you pay at the pharmacy: deductible, copays, and coinsurance. This means your true total cost is the $2,000 cap PLUS annual premiums.

How do I choose the best Part D plan?

Enter your specific medications at Medicare.gov's Plan Finder tool. It calculates your total annual cost for each available plan considering premiums, deductible, copays, and formulary coverage. The cheapest plan premium isn't always the cheapest total cost.

What is Extra Help for Part D?

Extra Help (Low-Income Subsidy) helps Medicare beneficiaries with limited income and resources pay Part D costs. It can reduce premiums to $0, eliminate the deductible, and lower copays to $1–11. Over 13 million people qualify but many don't apply.

Does IRMAA apply to Part D?

Yes, the same income brackets that trigger IRMAA for Part B also add surcharges to Part D premiums. Part D IRMAA ranges from ~$13 to ~$81/month depending on the income bracket. This is in addition to the plan's base premium.

Medicare Part D Cost Estimator

Estimate Medicare Part D prescription drug costs by coverage stage: deductible, initial coverage, coverage gap, and catastrophic coverage.

Total Annual Drug Costs

Monthly Plan Premium

Annual Deductible

Initial Coverage Coinsurance

Your OOP Drug Cost

$2,000.00

Capped at $2,000 (IRA)

Annual Premium

$420.00

Not counted toward cap

Total Annual Cost

$2,420.00

OOP + Premium

Cost by Coverage Stage

Stage	Drug Cost	You Pay
Deductible	$590.00	$590.00
Initial Coverage	$4,440.00	$1,110.00
Coverage Gap	$2,970.00	$300.00

Planning notes, formulas, and examples

About the Medicare Part D Cost Estimator

Medicare Part D has four distinct coverage stages, each with different cost-sharing rules. Understanding which stage you're in throughout the year is crucial for budgeting prescription drug expenses.

The stages are: (1) Deductible — you pay 100% until satisfied, (2) Initial Coverage — you pay a copay/coinsurance, (3) Coverage Gap (formerly the "donut hole") — you pay 25% of drug costs, and (4) Catastrophic Coverage. The model on this page uses the IRA-era $2,000 annual out-of-pocket cap.

This calculator estimates your Part D costs across all four stages based on your total annual drug spending. These are educational estimates only, not actual plan quotes.

When This Page Helps

Part D's four-stage structure confuses many beneficiaries, leading to surprise costs. It gives a clear breakdown of what you'll pay at each stage and your total annual out-of-pocket expense.

How to Use the Inputs

Enter the total annual retail cost of your prescriptions.
Enter the Part D plan monthly premium.
Enter the annual deductible amount.
Enter your coinsurance rate during the initial coverage stage.
Review costs at each stage and your total annual out-of-pocket.

Formula used

Stage 1 (Deductible): You pay 100% up to deductible amount
Stage 2 (Initial Coverage): You pay copay/coinsurance up to initial coverage limit
Stage 3 (Coverage Gap): You pay 25% of drug costs
Stage 4 (Catastrophic): follow the capped IRA-era structure used on this page
Total OOP = Sum of payments in all stages, subject to the annual cap modeled here

Example Calculation

Result: Total OOP: $2,000 (cap) | Premium: $420/yr | All-in: $2,420

With $8,000 in drug costs: $590 deductible + 25% coinsurance + 25% in coverage gap = exceeds the $2,000 OOP cap. Your OOP is capped at $2,000 thanks to the IRA provision. Including $420 in premiums, total annual cost is $2,420.

Tips & Best Practices

The $2,000 OOP cap modeled on this page is a major benefit from the Inflation Reduction Act structure.
Plan premiums do NOT count toward the OOP cap or deductible.
Compare plans annually during open enrollment — formularies and pricing change every year.
If you take expensive brand drugs, the coverage gap stage can be reached quickly.
These are educational estimates based on standard Part D structure; actual plans vary.
Extra Help / Low-Income Subsidy (LIS) is available for those with limited income and resources.

Understanding Part D Coverage Stages

The four stages create a complex cost journey that resets every January 1. Most beneficiaries with modest drug costs stay in Stage 1 or 2. Those taking expensive brand or specialty drugs may progress quickly through the full structure. The annual cap modeled on this page limits the worst-case out-of-pocket exposure.

Impact of the Inflation Reduction Act

The IRA materially changed Part D for high-cost patients by capping annual out-of-pocket exposure and spreading costs more evenly through the year.

Choosing the Right Plan During Open Enrollment

Part D plans change formularies, copays, and pharmacy networks annually. A plan that was cheapest last year may not be this year. Always re-evaluate during the Annual Enrollment Period (October 15 – December 7) using Medicare's Plan Finder with your medication list.

Sources & Methodology

Last updated: February 9, 2026

Frequently Asked Questions

The donut hole (coverage gap) was a stage where beneficiaries paid a much higher share of drug costs. It has been largely closed — beneficiaries pay 25% of drug costs in the gap, the same as the initial coverage stage. The IRA's $2,000 OOP cap further protects against high costs.