Guide
The bridge fund
Every conversion ladder has a five-year hole at the start where none of the converted money is reachable. What you put in that hole decides whether the plan survives — and it is the constraint that actually binds.
By The Roth Ladder · Published
Written against published statutory sources. Not a CPA or financial adviser — every formula is documented so you can check it.
The hole at the start
Convert in 2026 and that money becomes penalty-free on January 1, 2031. Nothing you convert is accessible before then. So between the day you retire and 2031, you have to fund your entire life from somewhere else — and you have to fund the conversion tax from there too.
That second obligation is the one people miss. The bill has two lines:
| What the bridge covers | Five-year total |
|---|---|
| Living expenses, at $40,000/year | $200,000 |
| Federal tax on the first five conversions | $28,050 |
| Total outside the IRA | $228,050 |
Those are the figures for a 40-year-old single filer with $500,000 pre-tax, converting to the top of the 12% bracket. The tax line is roughly 12% of the total — not a rounding error on top of living expenses, but a second household budget running alongside it.
Why the tax cannot come out of the IRA
It is tempting to have the custodian withhold tax from the conversion. Do not. Withheld tax is not converted — it is distributed, which means:
- It is taxed as ordinary income, the same as the conversion.
- It takes the 10% early-withdrawal penalty if you are under 59½ — the exact penalty the ladder exists to avoid.
- It never reaches the Roth, so it never starts a clock and never grows tax-free.
Converting $48,500 and withholding the tax means only $42,890 lands in the Roth, and you have paid a penalty on the difference. Pay from taxable money and the full $48,500 makes the trip.
The same ladder, two outcomes
Here is what the constraint looks like in practice. Identical conversion schedule, identical tax, identical everything — only the taxable balance differs:
| Taxable balance at retirement | Years covered | Outcome |
|---|---|---|
| $120,000 | 2 | Runs dry in 2028 |
| $320,000 | 19 | Holds through the first unlock |
The first row is the failure mode worth understanding, because on paper it looks like a good plan. The conversion schedule is tax-optimal. The bracket arbitrage is real. And it still breaks, because the account funding it empties before 2031.
What happens when it breaks
You do not get to pause. Living expenses arrive whether or not a tranche has seasoned, so the only options are an early Traditional IRA withdrawal with the 10% penalty, or withdrawing conversion principal that has not finished seasoning — which carries the same penalty. A ladder that fails in year four is usually more expensive than never having laddered at all.
How much is enough
Five years of expenses plus five years of tax is the floor, not the target. Three things argue for holding more:
- Sequence risk. The bridge is spent in its first five years, which is exactly when a drawdown does the most damage. A portfolio down 30% in year two has to fund the same spending from a smaller base, and there is no flexibility to wait for recovery.
- The tax bill grows. If your pre-tax balance is growing, each year's bracket-filling conversion is larger than the last, so the tax line rises across the bridge period rather than staying flat.
- Nothing about year six is a cliff edge. Once the first tranche unlocks you are drawing one year of spending from it — the taxable account still has to cover anything that tranche does not.
Six to seven years of combined spending and tax is a more defensible target than five. If that is out of reach, the honest conclusion is that the ladder is not yet the right tool — see the alternatives, which trade flexibility for not needing a bridge at all.
What counts as bridge money
| Source | Available before 59½? | Notes |
|---|---|---|
| Taxable brokerage | Yes | Capital gains tax on sale; the gains also count toward ACA MAGI |
| Cash and savings | Yes | No tax on principal; interest is ordinary income |
| Roth contributions | Yes | Contributed principal comes out anytime, no tax, no penalty, no clock |
| Roth conversions | Only after seasoning | Each tranche waits out its own five-year clock |
| Roth earnings | No | Needs the account clock satisfied and age 59½ |
| Traditional IRA / 401(k) | Not without penalty | The 10% penalty is the whole reason the ladder exists |
The Roth contribution line is the one people overlook in their own favor. If you contributed directly to a Roth IRA for years before retiring, that basis is accessible immediately and is genuinely part of your bridge. The five-year rule guide covers the withdrawal ordering that makes this true.
One interaction worth planning around
Selling taxable holdings to fund the bridge realizes capital gains, and those gains land in the same modified AGI that determines your ACA premium tax credit. So the bridge and the subsidy cliff are not independent problems — a year where you sell appreciated stock and convert can cross 400% of the federal poverty level on the combined total when neither would have done it alone.
Practically: harvest gains and convert in the same year only after checking where the combined figure lands. The subsidy cliff guide covers the cost of getting that wrong, and the calculator takes other taxable income as an input precisely so it shows up in the marginal rate.
Common questions
What is a bridge fund in a Roth conversion ladder?
A bridge fund is the money you live on during the five years before your first conversion becomes accessible. It has to sit outside the IRA — typically a taxable brokerage account, cash, or savings — because none of the converted money can be touched penalty-free until its five-year clock matures. It covers two things at once: your living expenses and the income tax on each conversion.
How many years of expenses do you need before starting a Roth conversion ladder?
At least five years of living expenses, plus five years of conversion tax. Five years is the floor rather than the target, because the first conversion is only accessible in year six and any market drawdown or unplanned expense in between has to be absorbed by the same account. Many planners hold six to seven years for that reason.
Can you pay Roth conversion tax from the IRA itself?
You can, but it defeats the purpose. Tax withheld from a conversion is treated as a distribution rather than as converted principal, so it is subject to income tax and the 10% early-withdrawal penalty if you are under 59½. It also shrinks the amount that actually lands in the Roth. Conversion tax should be paid from taxable money outside the account.
What happens if your bridge fund runs out before the first conversion unlocks?
You are forced into exactly the withdrawal you built the ladder to avoid: an early distribution from the Traditional IRA with the 10% penalty attached, or a withdrawal of unseasoned conversion principal, which carries the same penalty. Either outcome usually costs more than the bracket arbitrage the ladder was chasing, which is why solvency should be checked before the conversion schedule is optimized.
Do Roth contributions count as part of a bridge fund?
Regular Roth IRA contributions do, because contributed principal can be withdrawn at any time with no tax, no penalty, and no five-year wait. Conversion principal does not until its own clock matures, and earnings do not until the separate account clock is satisfied and you reach 59½. If you have years of direct Roth contributions, that basis is genuinely part of your accessible cash.
Check your own bridge · The ladder strategy · When a ladder is the wrong tool