One Withdrawal, Three Consequences: Understanding the Retirement Tax Domino Effect

Retirement often brings a welcome change in how you receive your income. Instead of relying on a paycheck, you may draw from a combination of retirement accounts, investments, Social Security, and other sources.

That flexibility can be valuable. It can also create complications that are easy to overlook.

A withdrawal from a traditional IRA, for example, does more than put money in your checking account. Depending on the amount and timing, it may increase your income taxes, affect your Medicare premiums, and reduce valuable tax deductions.

One decision. Several consequences.

Understanding how those pieces fit together can help you make more informed choices about where your retirement income comes from and when to take it.

The First Domino: A Higher Income Tax Bill

Withdrawals from traditional IRAs and pretax 401(k) accounts are generally taxed as ordinary income. The same is typically true when you convert money from a traditional retirement account to a Roth IRA.

If you withdraw $30,000 to fund a home improvement project, that $30,000 generally becomes part of your taxable income. If you convert $30,000 to a Roth IRA, the taxable portion of that conversion generally does the same, even though you may not be spending the money.

At first, the math can seem straightforward: Add the withdrawal to your income and apply your tax rate.

But retirement taxes rarely operate in isolation.

An additional withdrawal may move some of your income into a higher tax bracket or increase the portion of your Social Security benefits subject to federal income taxes.

To be clear, moving into a higher tax bracket does not mean all of your income is suddenly taxed at the higher rate. Generally, only the income falling within that bracket is taxed at that rate. However, the overall cost of the withdrawal may still be greater than expected once other income-related rules come into play.

Social Security Can Add Another Layer

Social Security benefits are not automatically tax-free.

Depending on your income, up to 85% of your benefits may be included in your taxable income. That does not mean you pay an 85% tax rate. It means up to 85% of the benefit amount may be subject to ordinary income taxes.

For federal tax purposes, Social Security uses a measure often called “combined income,” which generally includes adjusted gross income, nontaxable interest, and half of your Social Security benefits.

For individuals, taxation can begin when combined income exceeds $25,000. For married couples filing jointly, the threshold generally begins at $32,000. Higher thresholds of $34,000 for individuals and $44,000 for joint filers can result in up to 85% of benefits becoming taxable. Social Security Administration: Retirement Benefits

For someone whose benefits are not already taxed at the maximum level, an additional retirement-account withdrawal may cause more of those benefits to become taxable.

In other words, the withdrawal itself may generate taxes while also increasing taxes elsewhere on the return.

The Second Domino: Higher Medicare Premiums

Many retirees are familiar with Medicare premiums but less familiar with the income-related monthly adjustment amount, commonly called IRMAA.

IRMAA is an additional charge that can apply to Medicare Part B and Part D when your

income exceeds certain thresholds.

Unlike tax brackets, these premium adjustments operate in tiers. Crossing a threshold can move you into a higher premium category, even if your income exceeds that threshold by a relatively small amount.

The timing is another detail that often catches people off guard.

Medicare generally uses your tax return from two years earlier to determine whether an income-related adjustment applies. That means income reported on your 2026 tax return will generally be used when determining your 2028 Medicare premiums. Social Security Administration: Modified Adjusted Gross Income

A Roth conversion or large IRA withdrawal that feels manageable today may therefore result in higher Medicare premiums two years from now.

What That Can Look Like

Consider the published Medicare premium schedule for 2026.

For 2026, the standard Medicare Part B premium is $202.90 per month. The first income-related adjustment generally applies when income used for the Medicare determination exceeds $109,000 for an individual or $218,000 for a married couple filing jointly.

At the first higher tier:

• The Part B premium increases from $202.90 to $284.10 per person, per month.

• The Part D income-related adjustment adds another $14.50 per person, per month, on top of the underlying prescription plan premium.

  
  

Together, that is an additional $95.70 per month per person.

For a married couple with both spouses enrolled in Medicare Part B and prescription drug coverage, that could mean approximately $2,296.80 in additional premiums over a full year. Social Security Administration: IRMAA Sliding Scale Tables

Those figures illustrate the 2026 premium schedule. The actual thresholds and premium amounts that apply to 2026 income in 2028 may be different.

Still, the planning lesson remains the same: A withdrawal can carry costs that do not appear on your current tax return.

The Third Domino: Losing Part of the Senior Tax Deduction

Another consideration for 2026 is the enhanced deduction available to eligible taxpayers age 65 and older.

Under current law, qualifying individuals may receive an additional deduction of up to $6,000. Married couples filing jointly may receive up to $12,000 if both spouses qualify.

This deduction is separate from the existing additional standard deduction available to older taxpayers. It is also available whether you itemize deductions or claim the standard deduction.

However, the enhanced senior deduction begins to phase out when modified adjusted gross income exceeds:

• $75,000 for individual filers.

• $150,000 for married couples filing jointly.

  
  

The deduction is currently available for tax years 2025 through 2028, subject to the applicable eligibility requirements. IRS: Enhanced Senior Deduction

For retirees whose income is near or above those thresholds, an additional IRA withdrawal or Roth conversion may reduce the deduction they would otherwise receive.

That can increase the effective cost of the transaction.

For example, suppose a married couple expects their modified adjusted gross income to be approximately $145,000 before an additional withdrawal. If they take another $20,000 from a traditional IRA, their income may rise to approximately $165,000, placing them above the point where the senior deduction begins to phase out.

The withdrawal could therefore increase their taxable income directly while also reducing an available deduction.

It is also helpful to clarify a common misconception: The enhanced senior deduction does not eliminate taxes on Social Security benefits or change the existing rules used to determine whether those benefits are taxable. It is a separate deduction with its own eligibility requirements. IRS: Understanding Individual Tax Provisions

Why a Roth Conversion Can Still Make Sense

None of this means Roth conversions are a bad idea.

A well-planned conversion may help reduce future required minimum distributions, create a source of potentially tax-free retirement income, and provide additional flexibility later in retirement.

In some cases, accepting a higher tax bill today may still be worthwhile when compared with the potential long-term benefits.

The key is understanding the full cost before moving forward.

A $40,000 Roth conversion might appear reasonable when looking only at your current tax bracket. The analysis may change if that same conversion reduces a valuable deduction, increases the taxable portion of your Social Security benefits, or pushes you into a higher Medicare premium tier.

Those effects will not apply equally to everyone. Someone who has already reached the maximum taxable portion of their Social Security benefits, for example, may not see an additional change there. Likewise, someone well below a Medicare threshold may have more room to convert without triggering a surcharge.

Good planning is not about avoiding every tax or surcharge at all costs. It is about deciding whether the tradeoffs support your broader financial goals.

Strategies That May Help Limit the Domino Effect

The right approach depends on your income, account balances, age, charitable goals, and future financial needs. Still, several strategies can help you evaluate your options more effectively.

Spread Large Withdrawals or Conversions Across Multiple Years

Taking one large distribution may push your income above several thresholds at once.

Depending on your situation, dividing a withdrawal or Roth conversion over two or more tax years may help manage your tax bracket, protect available deductions, and reduce the likelihood of a Medicare premium surcharge.

Coordinate Which Accounts You Draw From

Traditional retirement accounts, Roth accounts, and taxable investment accounts do not all affect your income in the same way.

A qualified Roth IRA withdrawal is generally tax-free, while a withdrawal from a traditional IRA usually increases taxable income. Selling investments in a taxable account may create capital gains, but typically only the gain—not the entire amount withdrawn—is taxable.

Using a combination of account types may provide more control over your reported income.

Review Charitable Giving Options

If you are at least age 70½ and support charitable organizations, a qualified charitable distribution, or QCD, may be worth considering.

A QCD allows eligible individuals to transfer money directly from an IRA to a qualified charity. When properly structured, the distribution generally does not increase taxable income and may count toward an otherwise required minimum distribution.

That can make it especially useful for retirees who want to support a cause while managing income-related taxes and Medicare considerations. IRS: Qualified Charitable Distributions

Plan Around Required Minimum Distributions

Once required minimum distributions begin, those mandatory withdrawals may account for a significant portion of your annual taxable income.

Coordinating RMDs with other withdrawals, charitable gifts, and potential Roth conversions can help prevent avoidable surprises.

It is also important to remember that an RMD itself cannot be converted to a Roth IRA. If you are subject to an RMD, that required distribution generally needs to be addressed before converting additional retirement funds. IRS: Publication 590-B

Review the Numbers Before Year-End

Many retirement-related transactions must be completed by December 31 to affect the current tax year.

Reviewing projected income before the end of the year can provide time to adjust withdrawals, evaluate conversion opportunities, coordinate charitable giving, and prepare for potential Medicare premium implications.

Waiting until tax season may reveal what happened, but it usually does not give you the opportunity to change it.

A Better Retirement Decision Starts With the Full Picture

Retirement planning involves more than deciding how much money to withdraw.

The source of that withdrawal, its timing, and its impact on the rest of your financial picture can all influence what it ultimately costs.

At SkyBlue Wealth Advisors, we believe retirement income, tax planning, and investment decisions work best when they are considered together. Looking beyond the immediate transaction can help you identify potential consequences before they appear on a tax return or Medicare premium notice.

If you are considering a large withdrawal, a Roth conversion, or another significant financial decision this year, it may be worth asking a simple question:

What else might this decision affect?

TOP Private Wealth is an Investment Adviser registered with the U.S. Securities & Exchange Commission (SEC), principally located in the state of Connecticut. All views, expressions, and opinions included in this communication are subject to change.