A $4 Million 401(k) Can Create 3 Different Tax Bills
A $4 Million 401(k) Can Create Three Very Different Tax Bills — Here's How to Plan for All of Them
Four million dollars in a 401(k) can create three very different tax bills. The first may show up while you and your spouse are both retired. The second may hit whichever spouse lives longer. And the third could land on your children after you're gone. But here's the part most people miss: the largest tax problem may not happen on your own tax return—it may happen after the first spouse dies, when the household still has significant taxable assets but is filing under a completely different set of thresholds, or it may happen when your children inherit the account during the highest-earning years of their careers.
To walk through this, imagine a hypothetical couple—we'll call them Mark and Diane—who've accumulated $4 million between traditional 401(k)s and IRAs, along with some cash, a paid-off home, a small brokerage account, and almost no Roth money. They have two adult children in their 40s and regularly give to their church. On paper, they're in an excellent position. But instead of asking whether $4 million is enough, the better question is: who is eventually going to pay the tax on it?
Tax Return Number One: The Married Couple
While Mark and Diane are both alive, they file a joint return. Social Security covers part of their spending, they take additional withdrawals when needed, and eventually Required Minimum Distributions begin—generally starting at age 73 or 75 depending on birth year. Even if a $4 million pre-tax balance never grew another dollar, the first required distribution could exceed $150,000 under current RMD tables, and taxable retirement-account distributions are generally included in income whether the couple spends it or reinvests it. Add Social Security, possibly a pension, interest and dividends, and maybe a capital gain, and the couple can have substantial taxable income even without an extravagant lifestyle—income that may also affect Medicare Part B and Part D premiums through IRMAA, which generally looks back at income from two years earlier. This is the tax issue most people notice first. It may not be the most important one.
Tax Return Number Two: The Surviving Spouse
Fast-forward several years. Mark passes away, and Diane becomes the surviving spouse. Her financial life doesn't become half as expensive overnight—property taxes are still due, the home still needs maintenance, and she still has a car, insurance, utilities, healthcare costs, and everyday living expenses. But one Social Security benefit may disappear, since a surviving spouse generally receives the higher of the two benefits rather than both added together. And the tax return changes: Mark and Diane may still file jointly for the year Mark dies, but after that a surviving spouse without a qualifying dependent child will often move to single filing status—meaning the household can have much of the same taxable retirement money, but less favorable tax and Medicare thresholds.
This is what we call the surviving-spouse tax squeeze, and it changes how to think about Roth conversions. A conversion isn't only about whether Mark and Diane can pay a lower rate today than they might pay later—it can also be a spouse-protection decision. Moving some money from pre-tax to Roth accounts while both spouses are alive may reduce future required distributions and give the surviving spouse a source of retirement income that doesn't automatically increase taxable income when qualified withdrawals are made, since Roth accounts owned by the original owner are generally not subject to lifetime RMDs. That doesn't mean converting everything—a large conversion could create an unnecessary tax bill or increase Medicare premiums today. The point is modeling the conversion against two tax returns: the joint return they have now, and the single return one of them may eventually have later.
Tax Return Number Three: The Children
Suppose Diane eventually passes away and the remaining retirement account goes equally to their two adult children. Most non-spouse beneficiaries who don't qualify for a specific exception must empty an inherited retirement account by the end of the tenth year following the owner's death, and depending on timing, annual distributions may also be required during that period—with taxable inherited-account distributions generally included in the beneficiary's gross income. If both children are in their peak earning years, their inherited distributions don't receive a separate retirement tax bracket—those taxable withdrawals stack on top of income they already earn. A $1 million traditional IRA inheritance isn't the same as receiving $1 million of spendable cash; part of that account represents a future tax bill, and the compressed distribution timeline can make managing it much harder.
Compare three different $1 million inheritances: the first child receives $1 million in a traditional IRA, where withdrawals are generally taxable and subject to distribution rules; the second receives $1 million in a Roth IRA, still subject to beneficiary distribution rules but with most qualified withdrawals received tax-free; the third receives $1 million in a taxable brokerage account, where the basis is generally tied to fair market value at death, producing a very different capital-gains result. All three children inherited the same statement value, but they may not inherit the same amount after tax—which is why estate planning shouldn't stop with “divide everything equally.” Equal percentages don't necessarily create equal outcomes; which beneficiary receives which type of account matters.
The Charitable Opportunity
Once an IRA owner reaches age 70½, a Qualified Charitable Distribution may allow money to move directly from an eligible IRA to a qualified charity. When completed correctly and within the applicable limit, the qualified amount can be excluded from income and can count toward the owner's RMD—but the money generally has to move directly from the IRA to the charity; taking the distribution personally and then writing a separate check is not the same transaction. This can be especially valuable for someone who already intended to make the gift, since they're not donating more to receive a tax benefit—they're changing which account funds the giving. If Mark and Diane intend to leave part of their estate to charity, it may make sense to leave pre-tax retirement assets to the qualified charity while directing other assets to the children, since a tax-exempt charity may not face the same income-tax burden on those retirement dollars an individual beneficiary would.
Four Questions to Answer First
Before making a Roth conversion or changing a beneficiary form:
• How much of the $4 million are you likely to spend during your own lifetime?
• What could the surviving spouse's income and tax return look like after the first death?
• Who will inherit the remaining accounts, and what might their tax situation be when they receive them?
• How much of your estate do you genuinely want to leave to charity?
Once those answers are clear, the strategies fit into place: Roth conversions may shift some future taxable income away from the surviving spouse or children, QCDs may allow charitable giving to satisfy part of an RMD without adding to income, beneficiary designations may direct different account types toward the people or organizations that can use them most efficiently, and the withdrawal plan can determine whether the pre-tax balance grows unchecked or is intentionally managed throughout retirement.
There's no universal formula. For one family, converting part of the account may improve the lifetime result; for another, the current conversion cost may be too high. Is having $4 million in a 401(k) a problem? No—it's an incredible financial accomplishment. The problem is treating that $4 million as one simple number, when it may eventually be taxed on three different returns, under three different filing situations, across two generations.
At Cornerstone Wealth Planning, we help clients evaluate required distributions, Roth conversions, IRMAA, charitable giving, beneficiary decisions, investments, retirement income, healthcare, and estate planning as parts of one integrated retirement blueprint.
Whether you're located in Charlotte, NC or anywhere across the country, our team is ready to help you plan for all three tax returns on the way to a peaceful and purposeful retirement. Contact us today to schedule a free consultation.