Quick answer

You can deduct either state and local income taxes or state and local sales taxes on Schedule A (Form 1040), but not both. Pick the one that gives a larger total deduction after you compare: actual state income taxes withheld/paid versus the sales tax amount you can claim (actual receipts or the IRS sales tax tables). Keep in mind the SALT limit — state and local taxes (income, sales and property combined) are capped at $10,000 for most taxpayers (see IRS guidance).

Why this choice matters

Itemized deductions reduce taxable income and can lower your federal tax bill. Choosing the wrong deduction can cost you hundreds or thousands of dollars. The correct choice depends on:

  • How much state income tax you actually paid (withholding + estimated payments + state refunds repaid)
  • How much state and local sales tax you paid on big purchases and routine spending
  • Whether your itemized deductions exceed the standard deduction
  • Whether the SALT cap or other limits reduce your benefit

In my practice as a financial planner, I’ve run this comparison for clients who move between states with and without income tax, and the results can flip year to year—especially after large purchases like vehicles or home remodeling.

How each deduction works (step-by-step)

  1. Determine whether you will itemize. If your total itemized deductions (including mortgage interest, charitable gifts, medical expenses if deductible, and either your state income tax or state sales tax) exceed the standard deduction for your filing status, it makes sense to itemize. Otherwise, take the standard deduction.
  2. Compute your state income tax deduction: add state income tax withheld on Form W-2, estimated tax payments, and any state tax paid with an extension. Exclude state tax refunds you received (these may affect prior-year deductions).
  3. Compute your state sales tax deduction: either total the actual sales tax you paid using receipts for major purchases and add the IRS optional table amount for routine purchases, or use the IRS Sales Tax Deduction Calculator to get a starting point.
  4. Compare the two totals. Use Schedule A (Form 1040) to report whichever gives the larger deduction.

Authoritative IRS resources: see the IRS itemized deductions and About Form 1040 pages for filing instructions and tools (IRS: Itemized Deductions; Form 1040: Instructions).

Real examples (illustrative)

Example A — Big purchase year

  • State income taxes paid: $1,800
  • Major purchase: new car costing $40,000 with 8% sales tax = $3,200
  • Routine sales tax: $600 (estimated via IRS table)
    Sales tax total = $3,800 > $1,800, so sales tax deduction wins in this year.

Example B — High-income state with high withholding

  • State income taxes paid: $8,000
  • Major purchases: no large taxable purchases beyond ordinary spending
    Routine sales tax (IRS table) = $1,200
    Income tax deduction wins.

These examples show why it’s essential to add up actual numbers each tax year.

Key limits and rules to watch

  • You cannot claim both the state sales tax and the state income tax deduction for the same year — choose one on Schedule A. (IRS, Itemized Deductions)
  • SALT cap: state and local taxes (income, sales, and property) are combined and limited to $10,000 for married filing jointly and $5,000 for married filing separately in many years; confirm current thresholds before filing because legislation can change the limits. This cap is often the main driver for high-tax filers.
  • Standard deduction vs itemizing: if itemized deductions (including whichever state tax you choose) are less than the standard deduction, take the standard deduction instead.
  • Documentation: if you claim actual sales taxes paid for big purchases, keep receipts, bills of sale, or documentation. If you use the IRS optional table or the IRS Sales Tax Deduction Calculator, receipts for routine purchases are not required, but keep records supporting large purchases.
  • Nonresidents and part-year residents: special rules apply for deducting taxes paid to other states; follow state-specific guidance and IRS rules for apportioned amounts.
  • Alternative Minimum Tax (AMT): claiming certain state and local tax deductions may have little or no federal tax benefit for taxpayers subject to AMT.

References and tools:

Documentation checklist

  • W-2s showing state income tax withheld
  • Records of estimated state tax payments and any state return balance paid
  • Receipts, bills of sale, or closing statements for major purchases taxed by the state (cars, boats, home improvements, large appliances)
  • If using the IRS optional table, a record of how you reached the table amount (income worksheets or the IRS Sales Tax calculator)
  • State notices or returns showing tax paid to other states if claiming credit or deduction for out-of-state taxes
    Retain records for at least three years after filing; longer if you have unfiled returns or significant adjustments.

When sales tax deduction usually wins

  • You live in a state with no or low state income tax (e.g., Florida, Texas, Washington) but pay typical or high sales taxes.
  • You bought one or more big-ticket, taxable items (cars, boats, etc.) during the tax year.
  • Your routine spending on taxable goods is high and you live in a state with a relatively high combined state and local sales tax rate.

When income tax deduction usually wins

  • You live in a state with a high income tax rate and you have substantial tax withheld or had large estimated payments.
  • You had no large taxable purchases that would push your deductible sales tax above your state income taxes paid.
  • You’re claiming taxes paid to multiple states (for example, you worked in multiple states and paid income tax in those jurisdictions).

Special cases and state-specific issues

  • States with no income tax: residents typically choose sales tax unless their sales taxable purchases are minimal. But also consider state rules for deductibility and any credit systems.
  • Vehicle purchases and trade-ins: the portion of a vehicle purchase price subject to tax is usually deductible when using the sales tax option. Keep purchase contracts and registration as proof.
  • Refunds and carrybacks: state tax refunds can affect prior-year deductions. The IRS has rules that may require you to include prior-year refunds as income if you received a federal deduction for them.

Common mistakes to avoid

  • Forgetting the SALT cap and assuming all state tax paid will reduce federal taxes fully.
  • Neglecting to compare totals each year — the best choice can change after a single large purchase or a change in withholding.
  • Discarding receipts for large purchases; you’ll need documentation if you claim the actual sales tax paid.
  • Relying on memory instead of using actual numbers from W-2s, 1099s, state tax returns, and purchase records.

Actionable decision checklist (do this before filing)

  1. Gather W-2s, 1099s, state return receipts, and receipts for big purchases.
  2. Use the IRS Sales Tax Deduction Calculator or the IRS optional sales tax tables to estimate routine sales tax.
  3. Add up actual state income taxes paid this year (withholding + estimated payments).
  4. Add your likely itemized deductions (mortgage interest, charitable gifts, medical if deductible) and compare to the standard deduction.
  5. Choose the state tax deduction (sales or income) that gives the larger Schedule A total. Document your calculations and save proof.
  6. If your situation is complex (multi-state income, AMT exposure, or SALT planning for high earners), consult a tax professional.

Further reading on SALT planning and legislative effects

Final notes and professional disclaimer

This article explains how to compare the state sales tax deduction and the state income tax deduction. It is educational and does not replace personalized tax advice. Tax rules change and state laws vary — before filing, verify current IRS guidance and consider consulting a CPA or tax preparer for your specific situation.

Sources

(Edited and reviewed for accuracy and clarity by a financial content editor at FinHelp.io.)