Sometimes none of it -- even after OBBBA raised the cap to $40,000.
The calculator on this page's own index tells you your SALT deduction after the cap and phase-out. That figure is real, but it answers a narrower question than "does this help my refund." It only helps once your total itemized deductions -- SALT plus mortgage interest, charitable gifts, and anything else you itemize -- clear your standard deduction. And even then, only the slice that pushes you past the standard deduction is SALT's own contribution; the rest just matches ground the standard deduction covers for free.
Compare two totals: what you'd claim with SALT in the mix, and what you'd claim without it -- each the larger of itemizing or the standard deduction:
| Figure | Formula |
|---|---|
| Best claim with SALT | max(other itemized + SALT deduction, standard deduction) |
| Best claim without SALT | max(other itemized alone, standard deduction) |
| SALT's marginal benefit | the difference between the two |
That difference can land anywhere from $0 (SALT changes nothing) up to the full capped SALT deduction (SALT is entirely extra savings) -- which of those you get depends entirely on your other itemized deductions, not on the SALT figure alone.
All three use the 2025 rules. Filing status and MAGI only decide the SALT cap and
phase-out (via the same saltCapOutcome() the calculator uses); the
standard deduction depends only on filing status and tax year.
MAGI $200,000 (below the $500,000 phase-out threshold, so the cap is unreduced), $12,000 of state and local tax paid -- fully deductible, since it's under the $40,000 cap. $35,000 of mortgage interest and charitable gifts already clears the $31,500 married-filing-jointly standard deduction on its own.
| Item | Amount |
|---|---|
| SALT deduction (capped) | $12,000 |
| Other itemized deductions | $35,000 |
| Total itemized | $47,000 |
| Standard deduction (MFJ, 2025) | $31,500 |
| Best claim without SALT | max($35,000, $31,500) = $35,000 |
| Best claim with SALT | max($47,000, $31,500) = $47,000 |
| SALT's marginal benefit | $12,000 -- every dollar |
Identical SALT deduction, same $200,000 MAGI -- only the mortgage interest and charitable total changes, to $20,000, which alone falls short of the $31,500 standard deduction.
| Item | Amount |
|---|---|
| SALT deduction (capped) | $12,000 |
| Other itemized deductions | $20,000 |
| Total itemized | $32,000 |
| Standard deduction (MFJ, 2025) | $31,500 |
| Best claim without SALT | max($20,000, $31,500) = $31,500 (the standard deduction) |
| Best claim with SALT | max($32,000, $31,500) = $32,000 |
| SALT's marginal benefit | $500 -- not $12,000 |
$11,500 of this filer's $12,000 SALT deduction just closes the gap between their $20,000 of other itemized deductions and the $31,500 standard deduction they would have taken anyway. Only the last $500 is money the SALT deduction actually saved them.
MAGI $100,000, $8,000 of state and local tax paid (all deductible -- nowhere near the $40,000 cap). Only $3,000 of other itemized deductions.
| Item | Amount |
|---|---|
| SALT deduction (capped) | $8,000 |
| Other itemized deductions | $3,000 |
| Total itemized | $11,000 |
| Standard deduction (single, 2025) | $15,750 |
| Best claim without SALT | max($3,000, $15,750) = $15,750 |
| Best claim with SALT | max($11,000, $15,750) = $15,750 |
| SALT's marginal benefit | $0 |
This filer takes the standard deduction either way. Their $8,000 SALT deduction is real, correctly computed, and nowhere near the OBBBA cap -- and it adds exactly nothing to their refund, because their total itemized deductions never clear the $15,750 standard deduction.
The SALT deduction cap calculator computes the capped SALT figure this page uses as an input. It does not ask for your other itemized deductions or compare against the standard deduction -- that comparison is what this page walks through by hand. Nothing you enter anywhere on this site is uploaded.
No. The SALT deduction only helps at all if your total itemized deductions -- SALT plus mortgage interest, charitable gifts, and anything else you itemize -- exceed your standard deduction. If they don't, you take the standard deduction instead and the SALT cap, however generous, contributes nothing to your refund.
It means only part of your SALT deduction is genuine extra savings. If your other itemized deductions alone fall short of the standard deduction, the first slice of your SALT deduction just closes that gap -- matching ground the standard deduction already covered for free. Only the remainder, the part that pushes your total itemized deductions past the standard deduction, is SALT's own contribution.
It means your SALT deduction, even after the OBBBA cap and phase-out are applied, adds nothing: your other itemized deductions plus SALT still don't exceed the standard deduction, so you take the standard deduction either way and the marginal benefit of the SALT deduction is zero.
The calculator's deductible amount is the SALT-specific figure after the cap and phase-out -- a real number, but only half the picture. It says nothing about your other itemized deductions or the standard deduction, so a large capped SALT deduction can still add zero to your actual refund once the standard-deduction comparison is applied, exactly as the wholly-absorbed example on this page shows.
No. This page applies the published 2025/2026 standard deduction figures and ordinary itemize-vs-standard arithmetic to numbers you supply. It does not know your other itemized deductions, verify your filing status, or replace a qualified tax professional -- confirm your own numbers before filing.