How does the MAGI test for Roth IRA contributions differ from the MAGI test for the senior bonus deduction?
Executive summary
The MAGI test used to determine Roth IRA contribution eligibility is a specific IRS-defined modification of Adjusted Gross Income that adds back certain deductions (for example, student loan interest and foreign income exclusions) and can exclude taxable Roth conversions per IRS worksheets, and it drives phased contribution limits by filing status and year (e.g., 2026 phase‑out ranges and contribution caps) [1][2][3]. The available reporting does not include any reporting or authoritative guidance on a “senior bonus deduction” or a MAGI test specifically tied to such a deduction, so any direct comparison is not supported by the provided sources; where guidance exists for other MAGI‑based benefits, the definition of MAGI can and does vary by program [4][5].
1. What the Roth‑IRA MAGI test actually is — a rule with a worksheet and precise add‑backs
The Roth‑IRA MAGI determination starts with AGI from Form 1040 and then adds back a list of specific items (for example, IRA deductions, student loan interest, and foreign earned income exclusions) as set out in IRS Publication 590 and related worksheets, producing the MAGI used to determine whether a taxpayer falls below, inside, or above the Roth phase‑out ranges for contribution eligibility [1][2][3][4].
2. How that MAGI drives who can contribute and how much — phaseouts, limits, and practical effects
If MAGI is below the lower threshold for the filer’s status, a full Roth contribution is allowed; once MAGI enters the phase‑out range the permitted contribution is reduced until it reaches zero at the upper limit — IRS guidance and industry summaries give specific annual limits and ranges (for 2026 examples, single filers’ full contribution limit and phase‑out ranges and joint filer thresholds are published by the IRS and major custodians) [2][6][7].
3. The MAGI formula is program‑specific — the same phrase, different math for different benefits
MAGI is not a single universal number; the IRS and other agencies define MAGI differently depending on the program — the MAGI used for Roth contributions differs in which deductions are added back compared with the MAGI used to determine whether traditional IRA contributions are deductible or whether other tax credits apply, and authoritative articles and IRS worksheets explicitly warn that the MAGI calculation “can vary depending on the specific deduction or credit” [4][5].
4. Missing link: the “senior bonus deduction” is not documented in the supplied material
None of the provided sources define a “senior bonus deduction,” describe a MAGI test tied to such a deduction, or supply an IRS rule or worksheet for it; therefore a direct, source‑backed comparison between Roth‑IRA MAGI and a “senior bonus deduction” MAGI cannot be made from the materials supplied [1][4]. It is standard practice that whenever a benefit or deduction exists, its controlling MAGI definition will be found in the statute, Treasury/IRS guidance, or the program’s published instructions — none of which are in the current dataset for a “senior bonus” item [5].
5. Practical takeaways and where to look next for the missing piece
For taxpayers evaluating Roth eligibility, follow the IRS worksheet in Publication 590 and custodial guidance that lists exact add‑backs and the current phase‑out brackets and contribution limits [1][2]; for any claim about a “senior bonus deduction” and its MAGI test, authoritative confirmation must come from the specific program’s legal text or the IRS (or state) guidance — without those documents in hand, any comparison would be speculation rather than reporting [4][5]. Finally, readers should be alert that financial firms and advisers sometimes summarize MAGI rules differently for convenience, so always cross‑check with IRS worksheets to avoid being misled by simplified industry summaries [8][3].