Tax Bracket Creep: Why Your Retirement Tax Bill Keeps Growing

Why Your Retirement Tax Bill Keeps Climbing

Bracket creep in retirement is not just inflation eroding your purchasing power - though that is part of it. It is the compounding effect of multiple income sources each growing at their own pace, stacking on top of each other year after year. Here is what happens to a typical retiree's income over a 10-year period: Social Security receives annual COLA increases. In 2026, the COLA was 2.8%. In high-inflation years, COLAs can reach 5-8%. Each COLA increases your benefit check - and since up to 85% of benefits are taxable, each COLA also increases your taxable income. Required Minimum Distributions grow in two ways simultaneously. First, the life expectancy factor used to calculate your RMD decreases every year, forcing a higher percentage withdrawal. Second, if your account earns investment returns greater than your withdrawal rate, the balance itself grows - meaning a higher percentage of a higher balance. Pension COLAs, where they exist, add taxable income without any corresponding deductions or offsets. Meanwhile, the tax bracket thresholds do adjust annually for inflation - but they adjust based on general CPI, which may not keep pace with the specific factors driving retirement income growth. RMD percentages increase on a fixed actuarial schedule regardless of inflation. Social Security COLAs often track actual senior spending, which tends to run higher than general CPI. The net result: a retiree who starts in the 12% bracket at age 65 may find themselves firmly in the 22% bracket by age 75, and potentially approaching the 24% bracket by 85, without ever making a single decision to increase their spending or income.

The 10-Year Projection That Changes Everything

Let's build a concrete 10-year projection for a married couple retiring at 65 with the following starting income picture: $36,000 in combined Social Security, $18,000 in pension income, and a $500,000 combined traditional IRA balance. RMDs begin at 73. At age 65 (before RMDs): Combined gross income is $54,000. After the standard deduction for married filers ($32,200 in 2026, with additional amounts for age 65+), taxable income is approximately $21,800. Federal tax rate: mostly 12% bracket. Effective rate: roughly 8-9%. Comfortable. At age 73 (first RMD year): Eight years of Social Security COLAs at an average 2.5% have grown Social Security to approximately $43,800. Pension with 2% COLA has grown to $21,000. RMD on the $500,000 balance (which has grown to approximately $700,000 at 5% annual growth) is $700,000 divided by 26.5, or $26,415. Total gross income: $91,215. After deductions, taxable income roughly $58,000. Federal bracket: 22%. Social Security now 85% taxable. Effective rate: 14-16%. At age 83 (10 years of RMDs): Social Security has grown further via COLAs to approximately $48,500. Pension income approximately $23,200. IRA balance, reduced by RMDs but with remaining growth, might be $650,000. RMD at 83 is $650,000 divided by 17.7, or $36,723. Total gross income: $108,423. Social Security 85% taxable, adding $41,228. Effective federal rate approaching 18-20%. That is a doubling of the effective tax rate over 18 years - not because this couple did anything differently, but because the mechanics of retirement income pushed them up relentlessly.

The IRMAA Ratchet Effect

Layer IRMAA on top of the bracket creep calculation, and the picture becomes even more costly. Because IRMAA thresholds are not inflation-indexed at the lower tiers, more retirees cross into surcharge territory every year without any active change in their behavior. In the example above, the couple starts at age 65 with $54,000 in income - well below the $218,000 IRMAA threshold for married filers. They likely pay no IRMAA. By age 73, their gross income has climbed to over $91,000. Still below IRMAA thresholds for married filers. But by age 78-80, continued COLA increases, growing RMDs, and any investment income from taxable accounts could push their MAGI above $218,000 - the first IRMAA tier for married filers. Suddenly their Medicare costs jump by nearly $2,000 per year, and future increases become harder to avoid. This gradual IRMAA creep is insidious because each step happens slowly. You do not cross a threshold dramatically - you inch over it, and then the cliff structure of IRMAA penalizes you for $1 over the line as much as for $10,000 over the line. The only defense is systematic income management: converting to Roth before these income levels are reached, using tax-free income sources, and monitoring MAGI carefully against the IRMAA brackets each year.

Why Inflation Makes Bracket Creep Worse, Not Better

You might assume that high inflation helps retirees with bracket creep, because the IRS adjusts bracket thresholds for inflation annually. In accumulation phase, that is largely true. In distribution phase, it is more complicated. The tax bracket thresholds do adjust with CPI each year. But the Social Security taxation thresholds - the $25,000/$32,000 and $34,000/$44,000 combined income thresholds - have never been adjusted since 1983 and 1993. Inflation does not help you there. RMD factors also do not adjust for inflation. The percentage increase in your required withdrawal is actuarial - fixed by life expectancy tables - and has nothing to do with the inflation rate. So when inflation is high, here is what happens: Social Security COLAs increase faster, pushing more benefits into taxable territory against frozen thresholds. Your investment accounts may grow faster in nominal terms (though not necessarily real terms), generating higher RMDs. But the Social Security taxation thresholds sit fixed at 1983 and 1993 levels. High inflation years actually accelerate bracket creep in retirement, because the indexed parts (bracket thresholds) rise with CPI, but the non-indexed parts (SS taxation thresholds) stay frozen. The gap between what you earn and what stays tax-free narrows over time in an inflationary environment.

Getting Ahead of the Creep Before It Starts

The most effective time to address retirement bracket creep is before it begins - in the years between retirement and age 73 when your income is typically at its lowest point. During this window, Roth conversion planning offers the clearest path to reducing future bracket creep. Every dollar converted to Roth during low-income years permanently reduces future RMDs - and the growth on converted amounts is free from tax forever. A $50,000 Roth conversion at age 67 in the 22% bracket costs $11,000 in tax. But if that $50,000 grows to $85,000 by age 80 and would have been distributed at a 24-26% effective rate, you have saved $7,000-$9,000 in tax on the growth plus avoided the RMD escalation. Building tax-free income sources - Roth accounts, HSA funds, life insurance cash value - provides the distribution flexibility needed to manage bracket creep actively in retirement. Instead of being forced to take only taxable income, you can blend taxable and tax-free sources to stay within a specific bracket or below an IRMAA threshold. Finally, do the 10-year projection. Use the retirement tax calculator to model your income trajectory from today through age 85. See where the bracket escalation occurs, where IRMAA kicks in, and how much of your Social Security becomes taxable over time. The earlier you can see the curve, the more runway you have to flatten it.