Tax Traps to Avoid When Receiving a Lump Sum

Imagine receiving a $1,000,000 inheritance in 2026. You feel relief, maybe even excitement. Then you cash everything out at once-liquidating an inherited traditional IRA, selling a brokerage portfolio, and depositing the proceeds. By April 2027, your tax bill exceeds $250,000 after federal income tax, state taxes, capital gains tax, and medicare surcharges you never saw coming. A lump sum can create significant tax liabilities if not handled properly, and receiving a lump sum can push you into a higher federal income tax bracket overnight.

Lump sums arrive through many doors: inheritances, business sales, legal settlements, retirement plan cash-outs, NIL deals, or pension buyouts. Each carries different tax treatment, and the tax traps waiting inside each one are distinct. This article walks through seven specific traps and the practical steps you can take to reduce income tax, capital gains tax, and future required minimum distributions (RMDs).

At Third Act Retirement Planning, we are a fee-only, fiduciary firm in Marietta, Georgia that specializes in sudden wealth and retirement tax planning. Our approach integrates biblical wisdom about stewardship, because protecting wealth and using it purposefully are two sides of the same coin.

Know What Kind of Lump Sum You're Receiving (It's Not All Taxed the Same)

The first step is classification. Whether your money comes from a 401(k) distribution, brokerage inheritance, business sale, lawsuit settlement, or NIL contract matters enormously, because each triggers different income tax and capital gains rules. Lump sums from pre-tax retirement accounts are treated as ordinary income in the calendar year received. But an inherited brokerage account? Only the gain above the stepped-up basis is taxable. Getting this wrong on your return can alter your alternative minimum tax exposure, your eligibility for tax credits and tax deductions, and your capital gains tax rate.

Don't assume all $1,000,000 is taxed the same way. The SECURE Act requires non-spouse beneficiaries to withdraw inherited IRA funds within 10 years, compressing what used to be decades of tax-deferred growth into a much shorter window.

Trap #1: Treating the Entire Lump Sum as Spendable Cash in One Year

Consider a 62-year-old who cashes out a $750,000 401(k) in 2026. On top of their $150,000 base salary, this cash-out jumps them from the 22% marginal rate into the 35% federal bracket. The federal tax bill alone exceeds $200,000-before state taxes.

A large one-year spike in adjusted gross income can:

• Push you into higher tax brackets, creating a higher effective tax rate on every additional dollar.

• Trigger the 3.8% Net Investment Income Tax on investment income above income thresholds ($200,000 single, $250,000 married filing jointly).

• Accelerate phaseouts of tax credits, certain deductions, and even the standard deduction benefits relative to your overall tax situation.

• Inflate taxable income so dramatically that your healthcare costs rise via Medicare premium surcharges two years later.

A lump sum payout can artificially inflate your adjusted gross income, affecting everything from education credits to retirement income planning. Basing spending decisions on past performance of markets instead of tax reality can create dangerous shortfalls.

Alternatives exist: partial withdrawals spread across future years, direct rollovers into tax deferred retirement accounts, installment sale structures for business exits, or deferring income strategically to keep each year's taxable income below damaging income limits.

Trap #2: Ignoring Rollover Options and Mandatory Withholding on Retirement Lump Sums

Most employer plan lump-sum distributions qualify for rollover to an IRA or another qualified plan, which can defer the income tax hit entirely. But the mechanics matter.

• Direct rollover vs. 60-day rollover: A direct trustee-to-trustee rollover avoids mandatory tax withholding from distributions. If the plan pays you directly instead, the IRS mandates a flat 20% tax withholding for lump sums from employer retirement plans-and that 20% may be far too little if your marginal rate is 32% or 37%.

• The 60-day clock: You must roll over a retirement lump sum within 60 days to avoid taxation. If you miss the deadline, the entire amount becomes fully taxable income that year. You must also replace the withheld 20% from your own funds, or that portion is treated as a taxable distribution.

• Underpayment risk: Failure to withhold enough tax from a lump sum can result in IRS underpayment penalties. The penalty for cashing out a retirement account may depend on the source of the money-early distributions before age 59½ can also carry a 10% additional penalty.

Your plan administrator will issue IRS Form 1099-R by January 31 following the distribution year. You can file Form W-4R to request additional withholding if your total 2026 tax picture warrants it.

If you plan to retire or change jobs in 2026, don't request a cash lump sum from your 401(k) before you understand rollover rules. Seek tax advice before making irreversible elections.

Trap #3: Overlooking Capital Gains and Net Unrealized Appreciation (NUA)

Not every retirement lump sum is pure ordinary income. Employer stock inside a 401(k) can qualify for net unrealized appreciation treatment, and ignoring this is one of the costliest tax traps.

• How NUA works: The cost basis of employer stock is taxed as ordinary income in the distribution year. But the NUA-the growth in value-is taxed later at long term gains rates when you eventually sell the stock, rather than at ordinary income tax rates.

• Concrete example: An employee leaves in 2026 holding $300,000 of company stock in their plan with an $80,000 cost basis and $220,000 of NUA. If they distribute the stock properly, they owe ordinary income tax on $80,000 now and long-term capital gains tax on $220,000 when sold. If they mistakenly roll it all into an IRA, they lose NUA treatment and all $300,000 is taxed as ordinary income upon ira withdrawals.

Other capital gains traps to watch:

• Selling inherited or windfall assets in the same year as the lump sum stacks capital gains on top of already-high income, potentially pushing you into the 20% long-term rate.

• Selling investments held for less than a year incurs higher taxes than holding them more than a year.

• Capital gains can trigger a 3.8% net investment income tax for high income earners.

• Capital gains tax applies when cashing out a lump sum from selling an investment property, not just stocks.

• Tax loss harvesting can offset capital gains taxes effectively. If you hold positions with excess losses, you can sell them to reduce your net gain, and carry forward unused losses to future years.

A fee-only advisor can evaluate whether NUA, IRA rollover, or a combination makes the most sense for your tax situation.

Trap #4: Forgetting How a Lump Sum Can Trigger AMT, Social Security Taxes, and Medicare Surcharges

A sudden income spike doesn't just affect your basic tax bracket. It ripples into the alternative minimum tax, social security benefit taxation, and higher medicare premiums-three areas many retirees overlook.

Alternative Minimum Tax (AMT)

High-income households with large state and local tax deductions or incentive stock options could fall into AMT when a lump sum pushes 2026 income higher. The 2026 AMT exemption is $90,100 for single filers and $140,200 for married couples filing jointly, phasing out at $500,000 and $1,000,000 respectively. Run a dual calculation with a tax professional before year-end to spot potential AMT risk.

Social Security "Tax Torpedo"

Large IRA withdrawals or roth conversions funded by a lump sum can inflate provisional income-calculated as AGI plus half your social security benefits plus tax-exempt interest. Provisional income over $25,000 triggers Social Security taxes for individuals. For married couples, taxation starts at provisional income over $32,000. Up to 85% of social security benefits can be taxed at the highest tier. These social security taxation thresholds haven't adjusted for inflation in decades, making them easy to exceed.

Medicare Surcharges (IRMAA)

The income related monthly adjustment amount (IRMAA) uses a two-year lookback. Medicare surcharges begin at $103,000 MAGI for single filers in 2025; for 2026, the threshold rises to approximately $109,000 for singles and $218,000 for married couples. Your modified adjusted gross income from a 2026 lump sum can increase Medicare Part B and Part D premiums in 2028. The related monthly adjustment amount can push monthly premiums from about $203 to nearly $690 at the highest bracket. The monthly adjustment amount IRMAA is calculated each year, so multi-year tax modeling before electing a full lump sum is essential. Investing involves risk, but so does ignoring the tax implications of how you take your money out.

Trap #5: Missing Opportunities for Roth IRA Strategies and RMD Reduction

A big lump sum in your 50s or 60s can actually reduce future required minimum distributions and medicare premiums-if you plan strategically with roth accounts.

• Spread Roth conversions: Use lump-sum cash outside retirement accounts to pay the income tax cost of partial roth ira conversions across 2026–2030, instead of one massive event. Converting $100,000 per year for five years keeps you in a lower tax bracket each year. Converting $500,000 at once could push you into the 35% or 37% bracket and trigger IRMAA surcharges.

• Reduce RMD exposure: Required minimum distributions start at age 73 due to SECURE Act 2.0, and RMDs are taxed as ordinary income. Smaller pre-tax balances at rmd age mean smaller forced withdrawals, which reduce taxable income, capital gains stacking, and IRMAA exposure. Failing to take RMDs can incur a 25% penalty-a costly mistake. RMDs can increase your tax bracket and medicare premiums simultaneously.

• Roth advantage: Roth IRAs and roth accounts (once properly rolled over) generally have no lifetime required minimum distributions rmds, and qualified withdrawals are tax free withdrawals. This is especially powerful after a business sale or big settlement.

• Qualified Charitable Distributions: For those over 70½, qualified charitable distributions from IRAs can satisfy RMDs while keeping the distribution tax free. Directing funds to a qualified charity counts toward your RMD without increasing taxable income.

Timing matters: coordinate Roth strategies with Social Security claiming decisions and other income sources to avoid unintended bracket jumps. Every dollar saved from unnecessary tax burdens strengthens your financial goals.

Trap #6: Neglecting Estate, Charitable, and Legacy Planning When Sudden Wealth Arrives

Many people spend or invest their lump sum without updating wills, beneficiary designations, or charitable plans. This oversight creates avoidable estate and gift tax issues for heirs.

Estate and Gift Considerations

The 2026 federal estate and gift tax exemption is $15,000,000 per individual, with married couples able to shelter up to $30,000,000 through portability. Amounts above the exemption face a 40% tax rate. Estate planning strategies should be reviewed after tax law changes, especially given recent legislation. Gifts under $19,000 in 2025 avoid estate taxes, and a married couple can gift $38,000 without tax in 2025-a simple way to move assets over time and reduce a taxable estate using taxable accounts strategically.

SECURE Act and Inherited Retirement Accounts

Most non-spouse heirs must empty inherited traditional IRAs and employer plans within 10 years under the secure act, compressing retirement income recognition and tax liability into a shorter period than previous law allowed.

Charitable Planning

Donor-advised funds, charitable remainder trusts, and QCDs from IRAs after age 70½ align giving with biblical stewardship while managing RMDs and income tax. At Third Act Retirement Planning, legacy planning is not just about minimizing tax liability-it's about purposeful giving that reflects your values. Thomas Cloud, Jr., a Qualified Kingdom Advisor, helps families integrate faith-based priorities into every financial decision, ensuring that qualified expenses for charitable work and family legacy receive equal attention.

Trap #7: Relying on Rules of Thumb or Past Performance Instead of a Written Plan

Many new recipients of sudden wealth make decisions based on "rules of thumb"-the 4% withdrawal rule, "markets always come back," or "income tax rates will be lower in retirement." These shortcuts ignore the tax laws, bracket mechanics, and healthcare costs unique to your situation.

• Past performance of investments does not guarantee future results. Over-spending or too-aggressive investing with a fresh lump sum can create surprise tax bills when markets shift or tax laws change.

• A written, multi-year plan should coordinate withdrawal sequence from taxable accounts, tax-deferred, and Roth accounts to minimize tax liability each year.

• Capital gains realization strategy should be spread across several calendar years rather than compressed, reducing exposure to higher tax brackets and the 3.8% surtax.

• Major life events-retirement, business transitions, home purchases, relocation to higher or lower state taxes jurisdictions-must be modeled. Your filing status and income can change dramatically at tax time.

• The plan should be revisited annually as tax laws, brackets, Medicare income thresholds, and IRMAA tiers adjust for inflation.

A plan also accounts for deferring income in certain years and accelerating it in others based on projected long term gains, keeping you below critical income limits for credits and surcharges.

How Third Act Retirement Planning Helps You Navigate Lump-Sum Tax Traps

Third Act Retirement Planning is a fee-only, fiduciary firm serving individuals and families who have experienced sudden wealth and want peace of mind, purpose, and tax-smart stewardship. We specialize in helping people who have received inheritances, completed business exits, settled legal claims, or earned NIL income to avoid exactly the tax traps described above.

Our services include:

• Comprehensive tax mapping of your lump sum over the next 5–10 years, projecting RMDs, capital gains, state taxes, and medicare premiums so nothing catches you off guard.

• Investment management that considers tax location and timing of investment income to reduce avoidable taxes and help you reach your financial goals.

• Estate and legacy planning that incorporates charitable goals and biblical wisdom, guided by Thomas Cloud, Jr. as a Qualified Kingdom Advisor.

If you have received-or expect to receive-a significant lump sum in 2026, schedule a discovery call today. We charge no commissions. Our transparent fees are based on assets under management, and we provide ongoing guidance through changing tax laws. Because a lump sum is not just a financial event-it's a stewardship moment, and every dollar saved from unnecessary taxes is a dollar that can serve your family, your community, and your legacy.