US 2028 IRA Aggregation Rule

2028 IRA aggregation: all traditional IRA balances combined for pro-rata calculation on conversions. Defeats backdoor Roth if existing pre-tax IRA balance.

Pre-tax IRA balance ($)

After-tax IRA (non-deductible) ($)

Convert amount ($)

Marginal bracket %

Conversion Tax

—

Taxable Ratio

—

Taxable ratio	—
Taxable amount	—
Tax-free amount	—
2028 conversion tax	—

IRA aggregation rule (IRC §408(d)(2)): for pro-rata calculation on conversions, ALL traditional IRA balances (incl. SEP, SIMPLE) combined. Pre-tax balance defeats backdoor Roth — conversion becomes pro-rata pre/post tax. Workaround: roll pre-tax IRAs into 401(k) (if allowed) BEFORE converting after-tax IRA.

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Last updated May 2026. Sources: IRS Sec 408.