When the Tax Cuts and Jobs Act of 2017 imposed a $10,000 cap on the deduction for state and local taxes, it sent shockwaves through high-tax states across the country. Homeowners who had routinely deducted $15,000, $25,000, or more in combined property taxes and state income taxes suddenly found their deductions slashed by two-thirds or more. The cap became one of the most bitterly contested provisions in the tax code, spawning lawsuits, workaround schemes, and years of political trench warfare.
That battle is now largely over. The One Big Beautiful Bill Act, signed into law last year, raised the state and local tax deduction cap from $10,000 to $40,000, effective for tax years beginning in 2025. For the millions of Americans filing their 2025 returns during this spring's filing season, the change represents the single largest expansion of an individual tax deduction since the TCJA itself.
Who Benefits Most
The expanded SALT cap delivers its greatest benefits to a specific demographic: dual-income households in states with high income tax rates and elevated property values. Consider a married couple in Westchester County, New York, earning a combined $350,000. Their property taxes might run $18,000 annually, and their New York State income taxes roughly $15,000. Under the old $10,000 cap, they could deduct just $10,000 of that $33,000 total. Under the new $40,000 cap, they can deduct the full $33,000.
That additional $23,000 in deductions, at a 24% marginal tax rate, translates to roughly $5,520 in federal tax savings. For a family in the 32% bracket, the savings jump to $7,360. These are material numbers that will show up directly on refund checks or reduced tax-due amounts this spring.
The states where residents stand to gain the most are predictable: New York, New Jersey, Connecticut, California, Illinois, and Massachusetts lead the list. These states combine high income tax rates with property values that generate substantial property tax bills, creating the largest gaps between actual state and local taxes paid and the old $10,000 cap.
The Income Phaseout You Need to Know About
The expanded cap comes with an important limitation that Congress designed to prevent the wealthiest taxpayers from claiming an outsized benefit. The full $40,000 deduction is available only to households with a modified adjusted gross income of $500,000 or less, or $250,000 for married individuals filing separately.
Above that threshold, the deduction is reduced by 30 cents for every dollar of income over the limit, but it can never fall below the old $10,000 floor. This means a married couple earning $600,000 would see their maximum SALT deduction reduced by $30,000 (30% of the $100,000 overage), bringing their effective cap down to $10,000. For practical purposes, the expanded deduction phases out entirely at around $600,000 in MAGI for joint filers.
For 2026 returns filed next year, the cap increases slightly to $40,400, with the phaseout beginning at $505,000. The cap is scheduled to grow by approximately 1% annually through 2029 before reverting to $10,000 in 2030 unless Congress acts to extend it.
Itemizing vs. Standard Deduction: The New Math
The SALT cap expansion changes the itemization calculus for millions of households. Under the old $10,000 cap, many taxpayers who previously itemized found that the standard deduction, which has risen to $32,200 for married couples filing jointly in 2025, was higher than their total itemized deductions. With an additional $30,000 in potential SALT deductions now available, some of those taxpayers will find that itemizing is once again the better option.
The crossover analysis depends on individual circumstances, but here is a general framework. A married couple needs total itemized deductions exceeding $32,200 to benefit from itemizing. With the SALT cap at $40,000, a couple paying $25,000 in state and local taxes plus $15,000 in mortgage interest would have $40,000 in itemized deductions, well above the standard deduction threshold. Under the old cap, those same deductions would have totaled just $25,000, making the standard deduction the clear winner.
Tax professionals recommend running the numbers both ways before filing, as the optimal strategy varies significantly based on income level, state of residence, property values, and mortgage balance.
State-Level Workarounds: Are They Still Needed?
In the years since the original SALT cap took effect, several states created workaround mechanisms designed to help residents circumvent the limitation. The most common was the pass-through entity tax, which allowed business owners to pay state taxes at the entity level rather than the individual level, effectively converting a capped individual deduction into an uncapped business deduction.
With the SALT cap now at $40,000, many of these workarounds become unnecessary for taxpayers whose total state and local taxes fall below the new threshold. However, for business owners in high-tax states whose combined SALT exceeds $40,000, the pass-through entity tax election may still provide additional savings. Tax advisors recommend evaluating whether the workaround remains beneficial given the new cap level.
What Congress Giveth, Congress Can Take Away
It is worth noting the temporary nature of this expansion. The $40,000 cap is scheduled to revert to $10,000 on January 1, 2030, unless future legislation extends or modifies it. This sunset provision was included to manage the budgetary cost of the expansion, which the Congressional Budget Office estimated at approximately $300 billion over the initial five-year window.
History suggests that popular tax provisions, once enacted, are difficult to let expire. The original SALT deduction itself has existed in some form since the inception of the federal income tax in 1913. But the political dynamics around the provision remain charged, with lawmakers from low-tax states arguing that the expanded deduction amounts to a federal subsidy for high-tax state governance.
How to Claim the Expanded Deduction
Claiming the higher SALT deduction requires itemizing on Schedule A of Form 1040. Taxpayers should gather documentation of all state and local taxes paid during 2025, including state income taxes or sales taxes, real property taxes, and personal property taxes. For most filers, the relevant figures will appear on their W-2s (for state income tax withheld) and property tax statements from their county or municipality.
Tax preparation software has been updated to reflect the new $40,000 cap and will automatically calculate the deduction and any applicable phaseout based on the taxpayer's income. For those working with tax professionals, simply ensure your preparer is aware of the change, particularly if you switched to the standard deduction in recent years and need to revert to itemizing.
The Bottom Line
The quadrupling of the SALT cap from $10,000 to $40,000 is the most significant individual tax deduction change of the current filing season. For homeowners in high-tax states who have spent nearly a decade watching their deductions get clipped, this spring's return may finally deliver the relief they have been waiting for. But with the expansion set to expire in 2030, the window is finite. Tax professionals recommend maximizing the benefit while it is available and planning accordingly for the possibility that the higher cap may not survive beyond the current legislative horizon.
