How Roth Conversions Affect Medicare Premiums

Roth conversions can be a valuable retirement tax planning strategy. But many retirees are surprised to learn that large Roth conversions may also increase Medicare premiums, sometimes significantly.

The reason comes down to something called IRMAA, or the Income-Related Monthly Adjustment Amount. Medicare uses income from prior tax returns to determine whether higher-income retirees pay additional premiums for Medicare Part B and Part D coverage.

For retirees considering Roth conversions, understanding how IRMAA works can help avoid unintended costs and create more thoughtful long-term planning decisions.

What Is a Roth Conversion?

A Roth conversion occurs when money is moved from a pre-tax retirement account, such as a Traditional IRA or pre-tax 401(k) rollover IRA, into a Roth IRA.

The amount converted is generally taxable as ordinary income in the year of the conversion. In exchange, future qualified Roth IRA withdrawals may become tax free.

Many retirees use Roth conversions to:

• Reduce future Required Minimum Distributions (RMDs)
• Create future tax-free retirement income
• Manage long-term retirement taxes
• Leave more tax-efficient assets to heirs
• Create flexibility later in retirement

However, because Roth conversions increase taxable income, they can also affect Medicare premium calculations.

How Medicare Premiums Are Calculated

Medicare Part B and Part D premiums are based partly on something called Modified Adjusted Gross Income (MAGI).

Medicare looks back two years when determining premiums.

For example:

• Your 2026 Medicare premiums are generally based on your 2024 tax return.
• A large Roth conversion in 2024 could increase Medicare premiums in 2026.

When income rises above certain thresholds, retirees may pay IRMAA surcharges on top of standard Medicare premiums.

What Is IRMAA?

IRMAA stands for Income-Related Monthly Adjustment Amount. It is essentially a Medicare surcharge for higher-income retirees.

As income increases, Medicare Part B and Part D premiums increase in tiers.

Even a relatively modest increase in taxable income from a Roth conversion can push a retiree into a higher IRMAA bracket.

This often surprises retirees because:

• The surcharge may occur two years later
• The Medicare increase may not be obvious during tax planning
• One additional dollar of income can trigger a larger premium jump

Does That Mean Roth Conversions Are a Bad Idea?

Not necessarily.

In many cases, paying somewhat higher Medicare premiums temporarily may still make sense if the Roth conversion helps reduce future taxes over the long term.

The important point is not simply avoiding IRMAA at all costs. The goal is understanding the tradeoffs clearly.

For example, a retiree may intentionally complete Roth conversions:

• Before Required Minimum Distributions begin
• During lower-income retirement years
• After retiring but before Social Security starts
• Before a surviving spouse may face higher single-filer tax brackets

In some situations, a temporary Medicare surcharge may still produce meaningful lifetime tax savings.

Why Timing Matters With Roth Conversions

Timing can be one of the most important parts of Roth conversion planning.

A thoughtful strategy may involve spreading conversions over multiple years rather than converting a large amount all at once.

This may help retirees:

• Manage tax brackets more carefully
• Reduce the likelihood of large IRMAA jumps
• Coordinate conversions with Social Security timing
• Limit the impact on Medicare premiums
• Create more predictable retirement tax planning

Every situation is different. What makes sense for one retiree may not make sense for another.

Common Roth Conversion Mistakes Retirees Make

1. Ignoring Medicare Premium Effects

Some retirees focus only on federal income taxes and overlook how Roth conversions may affect Medicare costs later.

2. Converting Too Much in One Year

Large one-time conversions can push retirees into higher tax brackets and higher IRMAA brackets simultaneously.

3. Waiting Too Long

The years between retirement and Required Minimum Distributions are often valuable tax planning years. Delaying too long may reduce flexibility.

4. Looking at Taxes in Isolation

Retirement planning decisions are connected. Roth conversions can affect:

• Taxes
• Medicare premiums
• Social Security taxation
• Investment withdrawals
• Estate planning
• Long-term retirement income flexibility

How Beacon Financial Planning Helps Retirees Evaluate Roth Conversions

At Beacon Financial Planning, Roth conversion planning is typically viewed as part of a broader retirement income and tax planning strategy.

The goal is not simply reducing taxes in one year. The goal is helping retirees make thoughtful long-term decisions around:

• Retirement income
• Tax planning
• Social Security timing
• Medicare premiums
• Investment withdrawals
• Long-term financial flexibility

For many retirees, understanding how Roth conversions affect Medicare premiums is an important part of avoiding surprises and building a more coordinated retirement plan.

Final Thoughts

Roth conversions can be a powerful retirement planning tool. But because they increase taxable income, they can also affect Medicare premiums through IRMAA surcharges.

That does not automatically mean Roth conversions are bad. In many cases, they may still create substantial long-term benefits.

The key is understanding how taxes, Medicare, Social Security, investments, and retirement income decisions work together before making major planning moves.