SALT Deduction for Married Filing Separately: The Halving Rules (2026)
Married Filing Separately filers get exactly half of each SALT figure in 2026: a cap of $20,200 (half of $40,400), a phase-down threshold of $252,500 (half of $505,000), and a floor of $5,000 (half of $10,000). Each MFS spouse claims SALT on their own Schedule A using their individual MAGI, which effectively gives each spouse their own allocation of the combined limit.
The three halving rules for MFS
The OBBBA applies three separate halving rules to MFS filers. Each is an independent statutory provision, not a derived calculation:
| SALT parameter | Single / HoH / MFJ | MFS |
|---|---|---|
| Starting cap | $40,400 | $20,200 |
| Phase-down threshold | $505,000 | $252,500 |
| Phase-down floor | $10,000 | $5,000 |
| Reduction rate | 30% | 30% |
The reduction rate is the same across all filing statuses. Only the dollar amounts are halved for MFS. This means the phase-down progresses at the same pace relative to income above the threshold, but MFS filers start with less cap to lose.
Per-return, not per-person: the MFJ cap
One common misconception is that a married couple filing jointly receives $80,800in SALT deductions. They do not. The $40,400 cap is a per-return limit, and an MFJ return is one return. A married couple filing jointly gets a single $40,400 cap that covers all of their combined state and local taxes.
This is different from many other tax provisions where the MFJ amount is double the single amount. For SALT, the cap is the same whether you are a single filer or a married couple filing jointly. The only filing status with a different cap is MFS.
In practice, this means MFS actually gives each spouse their own slice. Two MFS returns at $20,200 each total $40,400, which equals the single MFJ cap of $40,400. The halving is mathematically consistent: MFS splits the joint cap across two returns.
How the MFS phase-down works
The MFS phase-down formula mirrors the standard formula with halved inputs:
Effective MFS cap = max($5,000, $20,200 - 30% x (MAGI - $252,500))
The cap reaches the $5,000 floor when MAGI hits approximately $303,167. Above that point, an MFS filer can deduct no more than $5,000 in state and local taxes regardless of how much they pay.
Each spouse calculates MAGI independently using their own income. If one spouse earns $302,500 and the other earns $60,000, only the higher-earning spouse faces a phase-down. The lower-earning spouse retains the full $20,200 cap.
Worked example: MFS at $280K
MFS filer, MAGI of $280,000, pays $18,000 in state and local taxes
MAGI: $280,000
MFS threshold: $252,500
Excess: $280,000 - $252,500 = $27,500
Reduction: 30% x $27,500 = $8,250
Calculated cap: $20,200 - $8,250 = $11,950
$11,950
SALT paid: $18,000
Deductible amount: 11,950 (capped)
This MFS filer's MAGI of $280,000 exceeds the $252,500 threshold by $27,500, triggering a $8,250 reduction. The effective cap is $11,950, and the $18,000 in SALT paid islimited to 11,950.
MFJ comparison at the same total income
MFJ couple, combined MAGI of $560,000, pays $36,000 total in state and local taxes
Combined MAGI: $560,000
MFJ threshold: $505,000
Excess: $560,000 - $505,000 = $55,000
Reduction: 30% x $55,000 = $16,500
Effective cap: max($10,000, $40,400 - $16,500) = $23,900
SALT paid: $36,000
Deductible amount: 23,900 (capped)
At the same combined income of $560,000, the MFJ couple gets an effective cap of $23,900 on a single return. If they filed MFS with income split evenly at $280,000 each, each spouse would calculate separately against the $252,500 threshold. The optimal choice depends on how income and deductions are distributed between spouses.
When MFS might still make sense for SALT
Although MFS generally produces a higher combined tax bill than MFJ, certain situations can make it worthwhile despite the halved SALT parameters:
- Income-driven student loan repayment. Some repayment plans use individual AGI when spouses file separately, which can dramatically lower monthly payments.
- Medical expense deduction. The 7.5% AGI floor for medical expenses is lower for the lower-earning spouse when filing separately, potentially unlocking a larger medical deduction.
- Liability protection. MFS limits each spouse's liability to their own return, which matters if one spouse has uncertain tax positions.
- Lopsided income. If one spouse earns far below the $252,500threshold and has significant SALT, that spouse retains the full $20,200 cap regardless of the other spouse's income.
Remember that MFS filers cannot claim the OBBBA above-the-line deductions (tips, overtime, senior bonus). The SALT cap is the one OBBBA provision that MFS filers retain, albeit at halved amounts. For more on MFS exclusions, see MFS and OBBBA: Why MFS Filers Are Excluded.
To model your own MFS vs. MFJ comparison, use the SALT cap calculator. For information on the per-return nature of the cap, see the per-taxpayer vs. per-return glossary entry.