How Much Should You Convert to Roth Each Year?

Quick Answer: 

Convert enough to fill your current tax bracket without spilling into the next one.Most retirees convert up to the top of the 12% or 22% bracket in their low-income years, while watching the lines that trigger Medicare surcharges and the net investment income tax. The right annual amount is the space between your income and your next costly threshold.

Key takeaways:

– Size each conversion by “filling” your current bracket, converting up to its top edge but not beyond.

– Watch 2 tripwires: the Medicare premium surcharge (IRMAA) and the 3.8% net investment income tax.

– The gap years between retiring and starting RMDs at 73 are usually the best window to convert.

– Roth conversions are a multi-year project, not a one-time move; map them across several years.

A Roth conversion moves money from a traditional IRA to a Roth, and you pay tax on the amount you convert this year to avoid tax on it forever after. The hard part isn’t whether to do it, it’s how much. Convert too little and you waste a low-bracket year; convert too much and you trigger higher rates and surcharges. Here’s how to find the right number.

How do you size a Roth conversion?

You size a conversion by filling your current tax bracket up to its top edge, a method called bracket-fill. Start with the income you already expect this year, subtract your deductions, and see how much room is left before you reach the top of your bracket. That room is roughly how much you can convert while staying at your current rate.

For 2026, per the IRS, a married couple’s 12% bracket runs up to $100,800 of taxable income, and the 22% bracket runs up to $211,400. If your taxable income is well below one of those ceilings, converting up to the ceiling lets you move money into your Roth at that lower rate. Pay the tax from a taxable account if you can, so the full converted amount lands in the Roth. For the timing side of the decision, see when should you do a roth conversion.

What is the bracket-fill method, step by step?

The bracket-fill method turns “how much” into a simple calculation. Work it in these steps:

1. Project your taxable income for the year before any conversion, including withdrawals, pension, and the taxable part of Social Security.

2. Pick your target bracket ceiling. Usually the top of the 12% or 22% bracket, whichever you’ve decided is your rate for the year.

3. Subtract your projected income from that ceiling. The difference is your starting conversion room.

4. Check the tripwires. Reduce the amount if the conversion would cross an IRMAA threshold or the net investment income tax line.

5. Convert, then verify late in the year. Recheck your actual income in November or December and top up or trim before year-end.

This keeps each conversion deliberate. You’re not guessing; you’re filling a defined space and
stopping at the edge.

What tripwires should you avoid when converting?

The 2 tripwires that turn a good conversion into an expensive one are the Medicare surcharge and the net investment income tax. A Roth conversion raises your income for the year, and that higher income can cross lines that cost you well beyond the conversion tax itself.

The first is IRMAA, the income-related surcharge on Medicare premiums. Per Medicare.gov, it’s based on your income from 2 years earlier, and for 2026 the first surcharge tier for a married couple starts once income tops $218,000. Cross that line with a conversion and your Medicare premiums jump 2 years later. The second is the 3.8% net investment income tax, which can apply once modified income passes $250,000 for a couple or $200,000 for a single filer. Convert up to your bracket, but stop short of these lines unless the long-term math clearly favors
pushing through. The details on the Medicare side are in do roth conversions raise your medicare premiums and how do you avoid IRMAA in retirement.

Why are the gap years the best time to convert?

The gap years, between the day you retire and the day required withdrawals begin at 73, are usually the best conversion window because your income is at its lowest. You have no paycheck, you may not have claimed Social Security yet, and RMDs aren’t forcing withdrawals. That combination often drops you into the 12% or even the 10% bracket for the first time in decades.

Converting during those years does 2 things at once: it moves money to tax-free status at a low rate, and it shrinks the traditional balance that would otherwise generate large, highly taxed RMDs later. Waiting until RMDs begin usually means converting on top of forced withdrawals, at higher rates. The gap years are a limited-time offer, and filling your low brackets during them is one of the highest-value moves in retirement.

How many years should you spread conversions over?

You should spread conversions over as many years as it takes to move the balance without ever jumping a bracket. Converting a large IRA all at once would spike you into the highest rates and blow past every tripwire. Doing a measured amount each year, filling the same bracket annually, moves far more money at low rates over time.

The practical approach is to map it: estimate how much you want in your Roth by the time RMDs begin, then divide the work across your gap years so each year’s conversion stays inside your target bracket. Revisit the map annually, because markets, tax law, and your income will shift. A multi-year plan almost always beats a single large conversion.