SALT Timing Plays for 2025–2029: Prepaying Property Taxes vs. AMT Interactions Under New Caps

📌 Background: SALT Deduction Caps

Since 2018, the $10,000 SALT cap has limited federal deductions for property, state income, and local taxes. That cap remains in effect until the end of 2025. After that, the post-TCJA “sunset” may reshape SALT limits depending on Congress’s actions. Taxpayers in high-tax states like New York, California, New Jersey, and Illinois feel the pinch most.

This makes timing plays between 2025–2029 crucial: when you pay your property tax bill could determine whether you receive any federal benefit.

💡 Prepaying Property Taxes: Does It Work?

Many taxpayers ask: “Can I prepay my 2026 property taxes in 2025 to claim a bigger deduction before the cap expires?” The IRS has clarified that:

• You can deduct prepaid property taxes only if the bill has been assessed (not just estimated).
• Prepaying in December 2025 for a 2026 assessment may work—if your local jurisdiction issues the bill early.
• Without an assessment, the IRS disallows the deduction.

This makes prepayment a valuable but limited tool. Smart taxpayers should monitor their county’s tax billing cycle closely.

⚖️ The AMT Trap

Even if you succeed in prepaying, you might not get the benefit if you are subject to the Alternative Minimum Tax (AMT). Under AMT rules:

• SALT deductions (including property taxes) are disallowed.
• If AMT applies, prepayments yield zero federal tax savings.
• High earners with large incentive stock option exercises, high state tax, or significant miscellaneous add-backs are most at risk.

That means prepayment strategies must be tested against an AMT projection. Otherwise, the deduction vanishes.

📊 Example: Timing Impact

🛠️ Planning Strategies for 2025–2029

• Coordinate SALT prepayments with your AMT projections.
• Use charitable giving bunching to offset AMT risk while accelerating deductions.
• Time bonus income or capital gains to years when AMT won’t apply.
• Leverage state-level pass-through entity (PTE) taxes if your state offers them (workarounds to SALT caps).
• Consider paying SALT in years where caps might loosen under new federal law (2026+ uncertainty).