Delay SS to 70 or Convert to Roth? The 62-70 Gap

The decision, resolved with math first

Meet Linda, 62, single, retiring this year in Ohio. She has a $900,000 traditional IRA, a $250,000 taxable brokerage account, and a Social Security Primary Insurance Amount (PIA) of $3,000/month at her full retirement age of 67. She keeps hearing two pieces of advice that sound contradictory: “delay Social Security to 70 for the 8% boost” and “do Roth conversions in your 60s while your income is low.” She has eight years — the 62-to-70 window — and she cannot fully fund both.

Here is the answer up front: Linda delays Social Security to 70, and spends the same low-income years converting from the traditional IRA — she does both, in that priority order, because delaying is the higher guaranteed return and delaying is precisely what creates the cheap bracket space conversions need. The mistake is framing this as either/or. The real constraint is not the tax code; it is the cash she has to live on while no Social Security check arrives and a conversion tax bill comes due.

Why the 62-to-70 window is the most valuable tax real estate you own

From 62 to 70, you can control your taxable income more precisely than at any other point in your life. No wages. No Social Security — if you delay. And no Required Minimum Distributions: under SECURE 2.0 §107, RMDs do not start until age 73 (if you were born 1951–1959) or 75 (born 1960 or later). That means for most of this window your only taxable income is whatever you deliberately create.

That control is the asset. With a $900,000 pre-tax IRA, Linda is staring at a future RMD problem. Because she turns 62 in 2026 (born 1964), her required minimum distributions do not start until age 75 under SECURE 2.0 §107 — but that only delays the reckoning, it does not shrink it. At 6% growth her balance reaches roughly $1.9M by age 75, forcing a first-year RMD near $78,000 (Uniform Lifetime divisor 24.6, IRS Pub. 590-B). Stack that on top of two Social Security checks and she is taxed in the 22%–24% bracket on income she is forced to take. The 62-70 window — and the bonus 70-75 years before RMDs begin — is her chance to drain that balance at lower rates before the IRS sets the schedule for her.

Lever 1: Delaying Social Security — the guaranteed 8%

Past full retirement age (67 for anyone born 1960 or later), Social Security pays a delayed retirement credit of +8% per year up to age 70 (SSA). For Linda, whose PIA is $3,000 at 67, waiting to 70 raises her monthly benefit by 24% to roughly $3,720 — before cost-of-living adjustments compound on the larger base. Claiming early at 62 instead would cut the benefit by about 30%, to roughly $2,100.

That 8%/year is not a market return you hope for; it is a contractual, inflation-adjusted increase backed by the federal government. No Roth conversion produces a guaranteed 8% real return. This is why delaying takes priority for anyone with average-or-better longevity: a single person who lives past roughly their early 80s comes out ahead by waiting, and the larger check is also longevity insurance — it protects you in exactly the scenario (a long life) where running out of money would hurt most.

Lever 2: Roth conversions — buying down the RMD tax bomb

A Roth conversion moves money from the traditional IRA to a Roth IRA, paying ordinary income tax now so that all future growth and withdrawals are tax-free — and, critically, the Roth has no RMDs during your lifetime (IRC §401(a)(9) applies to traditional accounts, not Roth IRAs). Every dollar Linda converts is a dollar that never appears in a future RMD calculation.

The play is to “fill brackets.” In 2026, the single brackets give Linda cheap room: the 12% bracket runs to $48,475 and the 22% bracket to $103,350 of taxable income. If she has little other income while delaying SS, she can convert tens of thousands of dollars at 12% and 22% — rates well below the 24%+ she would otherwise pay on forced RMDs later, and below what her surviving-spouse or heirs might face in a higher bracket.

Why you usually can’t max both — the cash-flow trap

Here is the conflict nobody mentions. Both levers consume the same scarce 62-70 runway, but in opposite ways on cash:

• Delaying SS means no benefit checks for eight years. Linda must fund eight years of living expenses from her portfolio.
• Converting to Roth means generating a tax bill — ideally paid from the taxable brokerage account, not from the IRA being converted (paying conversion tax out of the IRA wastes the strategy).

So the same brokerage account has to cover living expenses and conversion taxes and the foregone SS income, all at once. That is the binding limit. Linda’s $250,000 taxable account can support roughly $40,000–$60,000/year of combined living costs and conversion tax through the window — enough to delay SS and convert meaningfully, but not enough to convert the entire $900,000 down to zero. She prioritizes delaying (the guaranteed return) and converts as much as the cash and the brackets allow on top of it.

How the two levers reinforce each other

The good news: delaying SS makes conversions cheaper, not more expensive. With no Social Security from 62 to 70, Linda’s taxable income is low, so each conversion dollar lands in the 12% or 22% bracket instead of being stacked on top of benefits. The moment she claims at 70, up to 85% of her Social Security becomes taxable (single filers, above $34,000 combined income — thresholds set in 1983 and never inflation-indexed). Those benefits then fill her low brackets, and any remaining conversion gets pushed into 24%+. So the conversion window effectively closes when SS starts. Front-load conversions into the 62-70 gap.

Worked example: Linda’s 8-year plan

Linda delays SS to 70 and converts $70,000/year from 62 to 70, filling the 12% bracket and most of the 22% bracket each year (she uses the 2026 single standard deduction of $15,750 plus the age-65 add-on of $1,600 starting at 65). She pays the conversion tax from the brokerage account. Because she was born in 1964, her RMDs do not begin until age 75 (SECURE 2.0 §107) — so the table below compares her first RMD at 75 under each path.

By delaying and converting, Linda moves roughly $560,000 to Roth at an average rate in the mid-teens, cuts her age-75 RMD by more than half (from ~$78,000 to ~$38,000), and locks in a 77% larger Social Security check for life. The claim-at-62 path leaves the full ~$1.9M to be force-fed through RMDs at 24%+ while a smaller, permanently reduced benefit fills her low brackets. Same starting balance, materially different lifetime tax bill.

The sequence that makes it work

1. Confirm the longevity bet. Delaying SS wins if you reasonably expect to live past your early-to-mid 80s. Family history, health, and (for couples) the higher earner’s benefit as survivor protection all push toward delaying.
2. Map your cash runway. Add eight years of living expenses + projected conversion taxes. If your taxable and cash accounts can cover it, you can delay AND convert. If not, delaying still takes priority — you simply convert less.
3. Set an annual conversion target by bracket. Fill the 12% bracket ($48,475 single, 2026) at minimum; push into the 22% bracket ($103,350) if the IRA is large and cash allows.
4. Watch the IRMAA cliff once you turn 63. Medicare premiums at 65 are set by your MAGI two years earlier; the first Part B surcharge tier starts at $103,000 MAGI (single, 2026). Conversions made at 63 and after can raise your Part B premium, so size them against that cliff.
5. Pay conversion tax from taxable, not the IRA. Using IRA funds to pay the tax shrinks the amount that grows tax-free and may trigger an early-withdrawal penalty before 59½.

What most people get wrong

Myth: “Claim Social Security early so you don’t have to draw down your IRA — that frees up room to convert.” This is backwards. Claiming at 62 adds taxable benefits to your return (up to 85% taxable above $34,000 combined income, single). Those benefits fill your 12% and 22% brackets with Social Security instead of conversions, push any conversions you do attempt into higher brackets, and lock in a permanent ~30% benefit cut. Early claiming does not expand your conversion runway — it collapses it.

Myth: “Delaying Social Security lowers my RMDs.” Not directly. Delaying does nothing to your IRA balance. What it does is keep your taxable income low during 62-70 so that the conversions you make — which do lower RMDs — are taxed at the cheapest possible rate. RMD reduction comes from converting; delaying just makes converting affordable. The two levers do different jobs and only fully pay off together.

Myth: “It’s a coin flip, so just pick one.” It is not. For a single filer with a $900,000 pre-tax IRA and average longevity, delaying SS is the higher-confidence move (guaranteed +8%/year), and the conversions ride on top of the bracket room that delaying creates. The only people who should lean toward claiming earlier are those with serious health-driven short-longevity expectations or no other income to bridge the gap — and even they should convert what little room they have.

When the answer flips

• Short life expectancy. If you have a serious diagnosis or strong family history of early mortality, the longevity math that favors delaying weakens. Claiming earlier (and converting aggressively while in low brackets) can win.
• No bridge cash. If you have no taxable or cash savings to live on from 62 to 70, you may be forced to claim — though even a partial delay (claiming at 67–68 instead of 70) captures part of the credit.
• Small pre-tax balance. If your traditional IRA is modest (say under $300,000), the RMD tax bomb is small and conversions matter less; delaying SS is then almost purely about the larger check.
• Married couples. The higher earner’s delayed benefit becomes the survivor benefit, which strengthens the case to delay the larger PIA even further — while the lower earner may claim earlier to provide bridge income for conversions.

The decision lever

Stop treating this as a single fork. The 62-to-70 window is one runway you can spend on both objectives, in priority order: delay Social Security to 70 to lock the guaranteed +8%/year, then use those same low-income years to convert as much of the pre-tax IRA as your bracket targets and your bridge cash allow. Your real constraint is the cash that funds eight years of living expenses plus conversion taxes — not the choice itself. Size your annual conversion to fill the 12% and 22% brackets, keep an eye on the $103,000 IRMAA cliff from age 63, and front-load every conversion dollar before your SS check starts at 70 and slams the window shut.