$175,000 MAGI (single, head of household, qualifying surviving spouse) or $250,000 MAGI (married filing jointly) -- always exactly $100,000 above the phase-out threshold.
That $100,000 is not a separate, arbitrarily chosen number. It falls out of the other two numbers the statute already sets: a $6,000-per-person deduction reduced by 6 cents for every dollar of MAGI over the threshold. $6,000 ÷ 0.06 = $100,000 -- the exact amount of income headroom it takes to erase one person's deduction at that rate.
| Filing status | Phase-out starts | Fully phased out |
|---|---|---|
| Single / head of household / qualifying surviving spouse | $75,000 MAGI | $175,000 MAGI |
| Married filing jointly | $150,000 MAGI | $250,000 MAGI |
A single filer, one qualifying person, at four different MAGI levels:
| MAGI | Excess over $75,000 | Reduction (6% of excess) | Deduction |
|---|---|---|---|
| $100,000 | $25,000 | $1,500 | $4,500 |
| $150,000 | $75,000 | $4,500 | $1,500 |
| $175,000 or more | $100,000+ | $6,000 (capped) | $0 |
It is tempting to assume a joint return with two qualifying spouses -- up to $12,000 of deduction instead of $6,000 -- would need twice the MAGI headroom to phase out completely. It does not, because each spouse's own $6,000 phases out independently against the same household MAGI excess:
| Joint return, MAGI | Qualifying spouses | Combined deduction |
|---|---|---|
| $150,000 (at the threshold) | 2 | $12,000 |
| $200,000 | 2 | $6,000 |
| $250,000 | 2 | $0 |
| $250,000 | 1 | $0 |
Both the one-qualifying-spouse and two-qualifying-spouse joint returns reach $0 at the identical $250,000 MAGI -- the phase-out rate applies per-person, but the household MAGI it is tested against is the same number either way.
This portfolio's own auto loan interest deduction calculator rounds the MAGI excess up to the next $1,000 before applying its $200-per-$1,000 reduction -- so $100,001 of MAGI there already costs as much as $100,999 does. The senior deduction's 6%-per-dollar rate has no such rounding step: one extra dollar of MAGI here costs six-tenths of one cent, smoothly, all the way to the $100,000-wide phase-out range.
$175,000 MAGI for single, head of household, or qualifying surviving spouse filers. $250,000 MAGI for married filing jointly. Both numbers are the phase-out threshold plus exactly $100,000.
The deduction phases out at 6 cents per dollar of MAGI over the threshold, and the deduction itself is $6,000 per qualifying person. $6,000 divided by 0.06 is $100,000 -- the exact amount of MAGI headroom it takes to erase one person's $6,000 at a 6-cent-per-dollar rate.
No. Each spouse's own $6,000 phases out independently against the same household MAGI excess, so a two-qualifying-spouse joint return reaches $0 at the identical $250,000 MAGI a one-qualifying-spouse joint return does -- it does not take a higher income to zero out twice as much deduction.
No. The auto loan interest deduction rounds the MAGI excess up to the next $1,000 before applying its reduction, which can nudge the answer by up to $200 at an unlucky dollar amount. This deduction's 6%-per-dollar rate is continuous -- one extra dollar of MAGI costs six-tenths of one cent, not a jump to the next bracket.
Yes. This is a separate, additional deduction on top of both the regular standard deduction and the existing extra standard-deduction amount for taxpayers 65 and older. It is available whether you itemize or take the standard deduction.
The senior deduction calculator applies this same phase-out to your own MAGI and filing status, for one or two qualifying spouses. Nothing you enter is uploaded.