The 401(k) Rule That Matters Most Once You're Within 3 Months of Retirement

Thirty years of disciplined saving, consistent contributions, and careful investing brought you here. But the decisions that may most determine whether your retirement actually works are not the ones you made over that career. They are the ones you make in the next 90 days. If reaching your retirement goals is the destination, the final stretch before your last day of work could be where the road gets narrowest, and the errors get hardest to reverse.

Here is the rule that matters most right now, and the checklist that goes with it.

The single biggest risk you face right now

The biggest risk you could face right now is sequence of returns risk. If the market drops significantly in the first year or two after you retire, and you are pulling money out at the same time, the combination does permanent damage that good returns later cannot undo.

When you were in accumulation mode, a market drop was a temporary setback. You were buying more shares at lower prices, and time allowed the portfolio to recover. In withdrawal mode, the math reverses. Every dollar you pull out during a downturn is a dollar that cannot participate in the recovery. The portfolio shrinks faster, and the future growth base shrinks with it.

The result

Morningstar's 2026 State of Retirement Income research quantifies this directly: their base-case safe withdrawal rate for 2026 retirees is 3.9% annually for portfolios holding 30% to 50% in equities. Notably, Morningstar found that equity-heavy portfolios do not support higher withdrawal rates. Too much stock exposure during the withdrawal phase increases volatility and raises the probability that early losses will permanently derail the plan. Their research also found that retirees who encountered poor returns in the first five years of retirement and did not adjust spending were far more likely to exhaust their savings than those whose early years were positive.

Researchers call the window around retirement the "retirement risk zone," typically defined as the five years before and after the retirement date. Your portfolio is at its largest in absolute dollars during this window, meaning a percentage drop translates to the largest dollar loss you will ever experience.

What to do about it before you leave work

The goal is not to abandon your investment strategy, but to insulate near-term withdrawals so a market downturn does not force you to sell long-term assets at a loss.

Build a cash buffer for 1 to 3 years of withdrawals

The practical solution to sequence of returns risk is holding enough in stable, liquid assets, such as a money market fund, high-yield savings account, or short-term Treasury bills, to cover at least one year of planned withdrawals. With that buffer in place, a market downturn does not require you to sell equities at a loss. You live off the cash reserve while the market recovers, then replenish the reserve from the portfolio once conditions improve.

Review your asset allocation for withdrawal, not accumulation

Most default 401(k) allocations are calibrated for accumulation. A portfolio appropriate for a 45-year-old may carry more equity exposure than Morningstar's research supports for a stable withdrawal phase. A 30% to 50% equity allocation is not a rule, but it is Morningstar's best-case finding for a 30-year retirement with a 90% probability of success. The final 90 days is a reasonable moment to review and consider a deliberate, planned adjustment.

Establish your withdrawal order strategy

The sequence in which you draw from different account types significantly affects lifetime tax exposure. The commonly recommended order is: taxable brokerage accounts first, then tax-deferred accounts such as a traditional 401(k) or IRA, and Roth accounts last. Drawing taxable accounts first preserves tax-free Roth growth and allows you to manage taxable income in early retirement, which affects Medicare premiums, Social Security taxation thresholds, and future RMD amounts.

Confirm your RMD start date

Under the SECURE 2.0 Act, the required minimum distribution age for most people is 73, rising to 75 for anyone born in 1960 or later by 2033. Failing to take an RMD on time triggers a 25% penalty on the amount that should have been distributed, reduced to 10% if corrected promptly. People within a few years of 73 need to understand their specific start date and factor that into withdrawal planning.

One commonly missed exception: if you are still employed when you reach 73, and your 401(k) is held at your current employer, RMDs from that specific plan can be delayed until you actually retire. IRAs and 401(k) plans from previous employers do not qualify for this exception and must begin distributions on schedule.

Set your withdrawal amount against the 3.9% benchmark

On a $500,000 portfolio, Morningstar's base-case rate translates to $19,500 in the first year. On a $1 million portfolio, it is $39,000. These figures exclude Social Security and pension income. If your planned first-year withdrawal significantly exceeds 3.9%, that tension needs to be addressed before, not after, the first year of retirement begins.

What this is not

Getting within 90 days of retirement is not the moment for reactive moves. Liquidating the portfolio because the market looks uncertain, or making sweeping allocation changes based on headlines, could cause the kind of permanent damage these strategies are meant to prevent.

The goal is a deliberate, written plan thought through in advance. Most major 401(k) providers, including Fidelity, Vanguard, and Schwab, offer retirement transition tools at no additional cost. A fee-only financial planner who specializes in retirement income can translate these concepts into a personalized plan before the last paycheck arrives.

Bottom line

The final 90 days before retirement are the on-ramp to a phase that may last 30 years or more. Sequence of returns risk is real, the retirement risk zone is real, and building a stable buffer before you leave work is the most practical response to both.

A written retirement plan that addresses withdrawal order, asset allocation, RMD timing, and a cash buffer does not eliminate risk. It converts uncertainty from something that happens to you into something you have prepared for. That shift, made now rather than in the first difficult quarter of retirement, could be the one that matters most.