9 Common Mistakes That Are Quietly Shrinking Retirees' Social Security Benefits

Most conversations about Social Security focus on the claiming decision. But once benefits have started, a different set of financial mistakes could quietly reduce what actually lands in your bank account each month. Some of these reductions are temporary. Others compound year after year and never fully recover.

Here are the nine common ways retirees shrink their Social Security benefits without even realizing it.

Triggering the earnings test by working before FRA

If you're collecting benefits before full retirement age (FRA) and still earning income, the SSA's earnings test applies. 

In 2026, the SSA withholds $1 for every $2 you earn above $24,480 if you're under FRA all year. If you reach FRA, the threshold rises to $65,160, with $1 withheld for every $3 above that limit. While the withheld benefits aren't lost permanently, the short-term cash flow impact catches many retirees off guard.

Not tracking combined income and benefit taxation

If your combined income — adjusted gross income, nontaxable interest, and half of your annual Social Security benefit — exceeds $25,000 for individuals or $32,000 for joint filers, up to 85% of your benefit becomes federally taxable.

Many retirees don't realize their benefit is partially taxable until the tax bill arrives in April. The fix is calculating your provisional income before the year ends and adjusting withdrawals or withholding accordingly.

Pulling large IRA or 401(k) withdrawals without considering taxes

Withdrawals from traditional IRAs or 401(k) plans count as taxable income and flow directly into the provisional income calculation that determines how much of your Social Security is taxed.

A large distribution to cover a home repair or a one-time expense might tip you over the 85% threshold, creating an unexpected tax bill. Spreading withdrawals across tax years, or drawing from a Roth instead, might prevent this.

Letting Medicare Part B premiums eat into your check

Most retirees have their Part B premium deducted directly from their Social Security payment before it's deposited. 

In 2026, the standard Part B premium rose to $202.90 per month, up from $185 in 2025. That $17.90 monthly increase offsets a meaningful share of the 2026 COLA for many retirees. The premium rises most years, and because the deduction is automatic, many retirees don't notice the net deposit shrinking.

Getting blindsided by IRMAA surcharges

IRMAA is Medicare's income-based surcharge, calculated from your modified adjusted gross income (MAGI) two years prior. A high 2024 income, from IRA withdrawals, home sales, or final working years, could unexpectedly spike your 2026 Part B and Part D premiums.

In 2026, IRMAA surcharges begin at $109,000 MAGI for single filers and $218,000 for married couples, adding up to $8,279 per person annually at the highest tier.

Not requesting a new income determination after a life change

IRMAA recalculates annually using a two-year lookback, but major life changes, such as retirement, divorce, or a spouse's death, allow retirees to request a new determination based on recent income. Most retirees don't know this option exists.

Filing Form SSA-44 with documentation of your income reduction may immediately reduce or eliminate these surcharges, sparing you from waiting out the standard two-year lag for the system to correct itself.

Failing to adjust tax withholding on benefits

Social Security benefits may have federal taxes voluntarily withheld at 7%, 10%, 12%, or 22%. Many retirees skip withholding entirely, facing an unexpected year-end tax bill when combined income pushes them into higher brackets.

Filing Form W-4V with the SSA establishes this withholding, eliminating an April surprise. The right rate depends on your total income, including withdrawals, investments, and pensions.

Receiving an overpayment notice and ignoring it

Overpayments happen when the SSA pays too much, often due to missing or wrong information. Ignoring this notice allows the SSA to recover funds by withholding future benefits by $10 or 10%, whichever is more.

If you believe the notice is incorrect, you have the right to appeal or request a waiver. Acting quickly is critical as timely responses prevent automatic benefit suspension and preserve your options.

Retiring with fewer than 35 years of earnings

The Social Security formula averages your 35 highest-earning years. Retiring before hitting that threshold means the calculation fills missing years with zeros, permanently dragging down your average.

For someone with 30 years of work, those five zeros might slash monthly benefits by several hundred dollars. Working a few extra years, even part-time, replaces those zeros with actual earnings, meaningfully lifting your lifetime payout.

Bottom line

Many retirees accidentally shrink their Social Security income through taxes, Medicare premiums, and poorly timed withdrawals rather than benefit reductions themselves. Understanding these rules could help you protect more of the money you've earned throughout your working years.

To stretch your retirement dollars further, review your income sources before year-end. Coordinating IRA withdrawals, tax withholding, and Medicare thresholds may help prevent avoidable costs that quietly reduce your retirement income.