How to Calculate Your Medicare Premiums and IRMAA: Step-by-Step Guide

Navigating healthcare costs can feel a bit overwhelming, but calculating your Medicare premiums doesn't have to be a mystery! If your income is above a certain threshold, you might have to pay an extra amount called the Income Related Monthly Adjustment Amount (IRMAA).

In this friendly guide, we will walk you through how to calculate your total Medicare Part B and Part D premiums by hand. Grab a cup of tea, get your tax documents ready, and let's do this together!

The Prerequisites: What You Need First

Before we jump into the calculations, you will need to gather a few pieces of information:

1. Your Tax Return from Two Years Ago: Medicare uses your Modified Adjusted Gross Income (MAGI) from two years prior to determine your current premium. For example, your 2024 premiums are based on your 2022 tax return.
2. The Current Year's Medicare Rates: Medicare updates standard premiums and IRMAA brackets annually. We will use the official 2024 rates for our examples.
3. Your Part D Plan's Base Premium: Unlike Part B (which has a standard base rate set by the government), Part D prescription drug plans are run by private insurance companies, so your base premium depends on the specific plan you chose.

The Formulas

To find your total monthly cost, you will use two simple formulas:

Formula for Part B:

�KBLK0� Note: For 2024, the Standard Part B Premium is $174.70.

Formula for Part D:

�KBLK1�

Step-by-Step Worked Example

Let's put this into practice with a real-world scenario!

Meet Sarah. Sarah is a single filer. We want to calculate her 2024 Medicare premiums.

• Her 2022 MAGI was $135,000.
• Her chosen 2024 Part D plan base premium is $35.00.

Step 1: Find Sarah's Part B Surcharge

Looking at the 2024 IRMAA brackets for a single filer, an income of �KINL5�129,000 up to $161,000).

• For this bracket, the Part B IRMAA surcharge is $174.70.

Calculate her total Part B premium: �KBLK2�

Step 2: Find Sarah's Part D Surcharge

Using the same income bracket, we look up the Part D IRMAA surcharge, which is $33.30.

Calculate her total Part D premium: �KBLK3�

Step 3: Calculate the Grand Total

�KBLK4�

Nice job! You just calculated a complete Medicare premium by hand.

Common Pitfalls to Avoid

• Using the Wrong Tax Year: A very common mistake is looking at last year's tax return. Remember, Medicare always looks back two years!
• Using AGI instead of MAGI: Your Adjusted Gross Income (AGI) is not quite the same as your Modified Adjusted Gross Income (MAGI). For Medicare purposes, MAGI is your AGI plus any tax-exempt interest income you earned (like interest from municipal bonds). Be sure to add that back in!
• Assuming Part D is Free if you have IRMAA: Even if you choose a $0-premium Part D plan, if your income triggers IRMAA, you must still pay the Part D IRMAA surcharge directly to Medicare.

When to Use a Calculator

While doing the math by hand is a fantastic way to understand how the system works, using an online Medicare Premium Calculator is highly convenient when:

• You want to quickly compare different Part D plan options side-by-side.
• You want to project future costs based on estimated income changes.
• You are married filing jointly and want to quickly compute the combined household healthcare budget without looking up multiple tables.