Important Notice
This guide is general education, not personalized advice. The people in the examples are hypothetical, and every figure is illustrative. Historical results do not guarantee future returns.
For thirty years, dollar cost averaging was simply how your paycheck got invested. In retirement the question comes back in a different form. A large sum lands in cash, often at an emotional moment, and you have to decide how to put it to work.
The short answer from the research: investing at once has won about two-thirds of the time, and phasing in has beaten sitting in cash about two-thirds of the time. The more useful answer is that the entry schedule is a smaller decision than two others: what the money is for, and what stock-and-bond mix it should end up in.
Key Takeaways
- •A lump sum beat a three-month phase-in 68% of the time in global stocks from 1976 to 2022; phasing in beat holding cash 69% of the time (Vanguard, 2023).
- •The advantage of investing at once shrinks as the portfolio gets more conservative: 2.2% at the median for all stocks, 1.2% for 40% stocks and 60% bonds.
- •Money you will spend within about three years, such as the price of the next home, does not belong in stocks on any schedule.
- •A rollover that stays invested has no timing question. Months in cash is the timing bet.
- •If you phase in, keep it to three to twelve months, write the schedule down, and automate it.
What Does Dollar Cost Averaging Mean for a Retiree?
It means splitting a sum you already have into equal purchases spread over several months, instead of investing it on one day. A $600,000 inheritance might go in as $100,000 a month for six months.
During your working years you did this without choosing to. Each paycheck bought a slice of the 401(k), in good markets and bad. That kind of averaging is not a strategy; it is just the order in which money arrives. The real decision only appears when a large amount arrives at once. For readers in their sixties and seventies, that usually means one of these:
- An inheritance from a parent, sibling or spouse, in cash or a taxable brokerage account
- A 401(k) or 403(b) rollover after the last day of work
- The proceeds from selling a home, often the largest single check of a lifetime
- A pension taken as a lump sum instead of monthly income
- The sale of a business, a rental property, or a concentrated stock position
- A ladder of CDs or Treasuries maturing at once
Each of these carries a different tax profile and a different time horizon, which is why the answer is rarely just “invest it all today.” But the research gives a clear starting point.
What Does the Data Say About Lump Sum vs. Phasing In?
Investing at once has usually won. Vanguard compared a lump sum with a three-month phase-in across rolling one-year periods of global stock returns from 1976 to 2022. The lump sum finished ahead 68% of the time (Vanguard, “Cost averaging: Invest now or temporarily hold your cash?”, 2023). The reason is simple: stocks and bonds have beaten cash more often than not, so money waiting on the sidelines usually misses returns.
Vanguard's findings, 1976–2022
| Comparison | Winner, share of periods |
|---|---|
| Lump sum vs. three-month phase-in (100% stocks) | Lump sum, 68% |
| Phase-in vs. holding cash | Phase-in, 69% |
| Lump sum vs. holding cash | Lump sum, 70% |
| Lump sum vs. phase-in, waiting cash earning T-bill interest | Lump sum, 65% |
Global stocks measured by the MSCI World Index; bonds by the Bloomberg U.S. Aggregate Bond Index. Outcomes compared after one year.
How big is the gap? For a $100,000 investment in a 60/40 portfolio, the three-month phase-in averaged $107,453 after one year and the lump sum $109,360, about 1.8% more. At the median, the edge was 2.2% for an all-stock portfolio and 1.2% for a portfolio of 40% stocks and 60% bonds. The more conservative the mix, the less the entry schedule matters.
Two further findings matter for anyone holding a large check. First, longer phase-ins cost more; spreading the money over twelve months gives up more expected return than spreading it over three. Second, the lump sum lost in the worst quarter of historical outcomes. That is the whole trade: investing at once earns more most of the time and feels worse in the minority of cases when a decline follows soon after.
Our take
The 68% figure is not an argument for recklessness. It is an argument for deciding the right allocation first, then investing into that allocation without long delays. A phase-in that gets the money invested is far better than a plan to “wait for a pullback” that never gets executed.
How Does the Arithmetic Work?
Equal dollar amounts buy more shares when prices are low and fewer when they are high. That is the whole mechanism. Here is a hypothetical $600,000 phased in at $100,000 a month into a stock index fund whose price falls and then recovers.
Path A: prices dip, then recover
| Month | Share price | Invested | Shares bought |
|---|---|---|---|
| January | $100 | $100,000 | 1,000.00 |
| February | $90 | $100,000 | 1,111.11 |
| March | $80 | $100,000 | 1,250.00 |
| April | $95 | $100,000 | 1,052.63 |
| May | $110 | $100,000 | 909.09 |
| June | $105 | $100,000 | 952.38 |
| Total | Avg. price $96.67 | $600,000 | 6,275.21 |
Average cost per share: $95.61. At June's $105, the phased-in position is worth about $658,900. The same $600,000 invested in January (6,000 shares) is worth $630,000. Phasing in won by about $28,900.
Path B: prices rise steadily
Now let the price climb from $100 to $115 in $3 steps. The six purchases buy 5,594.12 shares, worth about $643,300 in June. The January lump sum's 6,000 shares are worth $690,000. Investing at once won by about $46,700.
Use the left and right arrow keys to read each year. The same figures are in the table or results beside the chart.
Phasing in pulls ahead when prices fall first and falls behind when they rise. It ends $28,900 ahead on Path A and $46,700 behind on Path B.
Neither path tells you what will happen next. The historical record says Path B, a market that drifts upward, has been the more common case, which is why the lump sum wins more often. Notice too that the phase-in's average cost ($95.61) came in below the average price ($96.67). That is arithmetic, not skill: equal-dollar purchases always produce a cost at or below the average price. It does not mean phasing in beats investing at once.
Why Is the Question Different at 65?
Because a bad first year hurts a retiree more than it hurts a saver. A 40-year-old who invests a bonus just before a 30% decline will buy cheaper shares with the next hundred paychecks. A 68-year-old who invests an inheritance just before the same decline may be selling shares at the low to pay for living expenses. That is sequence-of-returns risk, and it is the one legitimate financial argument for caution with a large sum late in life.
But the best tool against sequence risk is not the entry schedule. It is the allocation and the cash reserve. A retiree who holds one to two years of spending in cash and short-term bonds, and a 50/50 or 60/40 mix for the rest, does not need to sell stocks in a downturn regardless of when the windfall went in. Our asset allocation guide for 55 to 75 covers bucket strategies and glide paths, and the retirement cash reserve guide covers how much to keep liquid.
Three further differences apply to people in their sixties and seventies:
- Size relative to the portfolio. A $100,000 inheritance added to a $2 million portfolio barely changes its risk; invest it into your existing mix and move on. A $500,000 inheritance added to an $800,000 portfolio changes everything, and deserves a plan.
- Regret is a real cost. Behavioral research has long found that losses hurt more than equal gains please. If a lump-sum loss in the first year would push you to abandon a sound plan, a short phase-in is worth its modest expected cost.
- Grief and big decisions do not mix. Many windfalls follow a death. Parking the money in Treasury bills for a few months while you settle the estate is not market timing; it is prudence. Set a date to decide.
How Should You Handle an Inheritance, a Rollover or a Home Sale?
An inheritance in cash or a taxable account
Inherited stocks and funds generally take a new cost basis equal to their fair market value on the date of death (IRS Publication 551). Selling a concentrated position soon after inheriting it therefore tends to create little taxable gain, which makes it a good moment to rediversify into your own target mix. Once it is diversified, the lump sum or phase-in question applies as usual.
An inherited IRA is a different problem, governed by distribution deadlines rather than entry timing. See our guide to the inherited IRA 10-year rule.
A 401(k) or 403(b) rollover
Most rollovers have no timing question at all. If the money is already in a diversified mix and lands in a similar mix at the IRA custodian within days, you were never really out of the market. Leaving it in the IRA's cash sweep for six months “until things settle” is the market-timing decision.
Use a direct, trustee-to-trustee rollover. A plan distribution paid to you is subject to mandatory 20% withholding, and to avoid tax on the withheld part you must make it up from other funds when you deposit the money within 60 days. Separately, you can do only one IRA-to-IRA rollover of the 60-day kind in any 12-month period (IRS). Direct transfers avoid both problems.
Proceeds from selling a home
Divide the check by when you will need it. Money for the next home, a renovation, moving costs, or an entrance fee at a continuing-care community belongs in Treasury bills, a money market fund or CDs until it is spent. Only the portion you will not need for five years or more belongs in stocks, and that portion can follow the usual lump-sum logic.
On the tax side, a married couple filing jointly can generally exclude up to $500,000 of gain on a main home they owned and lived in for two of the last five years, and a single filer $250,000. A surviving spouse who sells within two years of the spouse's death and has not remarried can generally still use the $500,000 limit (IRS Publication 523). Our downsizing guide covers the move itself.
A pension lump sum or a business sale
A pension lump sum is first a question of whether to take it at all, since the monthly annuity is itself a bond-like asset. Our pension lump sum vs. annuity guide works through that choice. If you take the lump sum, roll it directly to an IRA and invest it into the allocation you would have held with the pension counted as a bond.
A business sale or a large block of one company's stock raises the opposite problem: getting out over time. Selling a concentrated position in stages across two or three tax years can spread the capital gains across lower brackets. That is dollar cost averaging in reverse, and it is often more valuable than the version for buying.
How Would This Work With a $500,000 Inheritance?
Take a hypothetical widow, Carol, 71. She has a $1.4 million IRA and brokerage portfolio held at 50% stocks and 50% bonds, Social Security of $3,100 a month, and a paid-off house. Her withdrawals run about 3.5% a year. Her brother leaves her a $500,000 brokerage account, almost all of it in one technology stock, which takes a new basis equal to its value on the date of his death.
First she decides what the money is for. She wants to help two grandchildren with college in the next four years, perhaps $80,000 in total, and otherwise to add to the family's eventual inheritance. So $80,000 goes into a Treasury bill ladder, and $420,000 becomes long-term money.
Next, the allocation. Carol sees no reason to change her 50/50 mix, so the $420,000 should end up as about $210,000 in stocks and $210,000 in bonds. She sells the single stock right away; with the new basis, the taxable gain is small. The $210,000 bond portion goes into her bond fund the same week, since bonds carry little of the risk that phasing in is meant to soften.
Finally, the schedule. Investing the $210,000 stock portion at once is the higher-expected-return choice. Carol admits a 25% drop in the first year would shake her, so she sets up six automatic purchases of $35,000, one a month, with the waiting cash in a Treasury money market fund. Going by Vanguard's numbers, the expected cost of that choice is a small fraction of her total portfolio. The expected benefit is a plan she will keep.
Why this order works
Purpose, then allocation, then schedule. Most of the risk decision happened in step two. By the time Carol chose a phase-in, only $210,000 of a $1.9 million household portfolio was affected, and only for six months.
How Should You Phase In If You Choose To?
Decide the destination first
Write down the target mix the money will end up in, and invest the bond portion at once.
Keep the window short
Three to twelve months. Longer schedules give up more expected return with little added comfort.
Hold the waiting money in T-bills or a Treasury money market fund
Not a checking account. Interest on Treasury bills is exempt from state and local income tax.
Automate every purchase
Set the dates and amounts at the custodian so no single purchase depends on the day’s headlines.
Do not pause on bad news
A decline during the phase-in is exactly when the schedule earns its keep. Skipping a purchase turns a plan into market timing.
Consider a hybrid
Half at once, half over six months, is a sensible compromise for a sum that is large relative to the rest of your portfolio.
The same logic runs in reverse once you are drawing income. Selling a fixed amount each month or quarter to fund spending is a systematic withdrawal, and pairing it with a cash reserve keeps you from selling stocks at a low. Our withdrawal order guide covers which accounts to draw from first.
Frequently Asked Questions
Is it better to invest an inheritance all at once or over time?
Historically, investing all at once has come out ahead about two-thirds of the time. Vanguard found a lump sum beat a three-month phase-in 68% of the time across global stock markets from 1976 to 2022. Phasing in still beat leaving the money in cash 69% of the time, so if a schedule is what gets the money invested, it is a reasonable choice. Decide the target stock-and-bond mix first; that matters more than the entry schedule.
How long should I spread out a lump-sum investment?
If you phase in, keep it short: three to twelve months. Vanguard found that the longer the phase-in period, the greater the cost, because more of the money sits in cash for longer. Put the schedule in writing, automate it, and hold the waiting money in Treasury bills or a Treasury money market fund rather than a checking account.
Should I dollar cost average a 401(k) rollover?
Usually there is nothing to phase in. A direct rollover moves money from the plan to an IRA, and if the new account buys a similar diversified mix within days, you were never out of the market. Leaving a rollover in cash for months is itself a market-timing bet. Use a direct trustee-to-trustee rollover to avoid the mandatory 20% withholding on a distribution paid to you.
What should I do with the proceeds from selling my house?
Start with when you will need the money. Proceeds earmarked for the next home, a move, or a care community within about three years belong in Treasury bills, a money market fund or CDs, not stocks. Only the portion you will not touch for five years or more belongs in your long-term portfolio, and that portion can go in at once or on a short schedule.
Does dollar cost averaging reduce risk?
It reduces the risk of regret about a single bad entry day, and it lowers risk temporarily because part of the money is in cash. It does not lower long-term risk: once the money is fully invested, the portfolio carries the same risk either way. A more conservative target allocation reduces risk far more reliably than a phase-in schedule does.
The Bottom Line
Investing a windfall at once has usually produced more money, and phasing it in has usually beaten waiting. Neither beats getting the allocation right. Separate the money you will spend soon, choose the stock-and-bond mix for the rest, invest the bond side now, and if a schedule for the stock side helps you sleep, keep it short and automatic.
Check the Allocation Before the Schedule
Map your accounts and see where a windfall moves your stock-and-bond mix.
Open the Asset Allocation Worksheet →Related Reading
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