What is the SALT deduction cap and how much did it change in 2025?

SALT is state and local income/sales tax plus property tax. The 2017 TCJA capped it at a flat $10,000. The One Big Beautiful Bill Act of 2025 raised that to $40,000 for 2025 and $40,400 for 2026, phasing back toward $10,000 for high earners and fully reverting to $10,000 in 2030.

How does the SALT cap phase-down work for high earners?

For 2026: cap = max($10,000, $40,400 − 30% × max(0, MAGI − $505,000)). For every dollar of MAGI above $505,000, the expanded cap shrinks by 30 cents, bottoming out at the original $10,000 TCJA floor once MAGI reaches roughly $606,000.

Is the mortgage interest deduction cap still $750,000?

Yes — the One Big Beautiful Bill Act made the $750,000 acquisition-debt cap permanent, removing the sunset that would otherwise have reverted it to the older $1,000,000 cap after 2025. Mortgages originated before December 15, 2017 remain grandfathered at the $1,000,000 cap.

What changed about the charitable deduction in 2026?

The existing 60%-of-AGI cap on cash gifts to public charities became permanent (it was scheduled to revert to 50%). But starting in 2026, a new rule requires charitable contributions to exceed 0.5% of AGI before any of it is deductible at all — a floor that didn't exist before.

The 2026 SALT Cap Jumped to $40,400 — Enough to Flip Many Households Back to Itemizing

We ran $25,000 in SALT, $18,000 in mortgage interest, $8,000 in cash charity, and $5,000 in medical expenses through the calculator at a $180,000 AGI, married filing jointly. Total itemized: $50,100, against a $30,000 standard deduction — itemizing wins by $20,100. Under the old $10,000 SALT cap, this same household would have deducted only $10,000 of that $25,000 in state and local taxes, dropping total itemized to $35,100 — still technically above standard, but by a much thinner margin that many similar households with slightly lower SALT bills would have missed entirely.

A cap increase, not a permanent fix

	2017-2024 (TCJA)	2025-2029 (OBBBA)	2030+
SALT cap	$10,000 flat	$40,000 → $40,400+ (indexed), phased down above $500K-505K+ MAGI	Reverts to $10,000
Mortgage interest	$750,000 acquisition debt	$750,000 (now permanent)	$750,000
Charitable cash cap	60% of AGI	60% of AGI (now permanent)	60% of AGI
Charitable floor	None	0.5% of AGI (new, starting 2026)	0.5% of AGI

The SALT expansion is explicitly temporary — scheduled to revert to the original $10,000 cap in 2030 — while the mortgage interest cap and the charitable AGI cap were made permanent in the same legislation. That combination means the tax planning window this creates for high-SALT-state homeowners has a real expiration date, unlike most of the other changes bundled into the same bill.

The phase-down formula, worked through

A household at $560,000 MAGI in 2026 — $55,000 over the $505,000 phase-down start — loses 30% × $55,000 = $16,500 of the expanded cap, leaving an effective SALT cap of $40,400 − $16,500 = $23,900. That’s still more than double the old $10,000 flat cap, but noticeably less than the full $40,400 headline figure — a detail easy to miss if a household assumes the expanded cap applies in full regardless of income.

Where this framework doesn’t apply

Your AGI is well above roughly $606,000. The SALT cap phase-down fully erodes the 2025 expansion at that point, returning the deduction to the original $10,000 TCJA floor.
You live in a low-tax state with no mortgage. Without significant SALT or mortgage interest, the standard deduction usually still wins comfortably.
You’re giving appreciated stock, not cash. Non-cash charitable gifts have their own valuation and AGI-limitation rules (generally 30% of AGI, not 60%).
Your itemized total is close to the standard deduction either way. When the gap is small, the extra recordkeeping of itemizing may not be worth it even if it technically wins by a modest margin.

What to actually do

Pull your actual SALT, mortgage interest, and charitable giving figures from last year’s return rather than estimating.
If you stopped itemizing after 2017, rerun the numbers now — the 2025 SALT cap expansion may have quietly flipped the answer.
If your AGI is near $505,000, work through the phase-down formula carefully rather than assuming the full $40,400 cap applies.
If charitable giving alone isn’t clearing the gap to itemizing, consider concentrating several years of gifts into one — see how charitable bunching turns wasted deductions into real savings.
Revisit the comparison every year through 2029, since both the standard deduction and the SALT cap figures are scheduled to keep changing.

Open the Standard vs Itemized Deduction Calculator → and run your own SALT, mortgage, and giving figures.