Year-End Tax Planning Guide (US)

Year-end tax planning is not about finding loopholes. It is about deciding which moves are worth modeling before the calendar closes. The best work happens in Q4 because you still have time to act.

Last reviewed: January 16, 2026.

Key takeaways

• The year-end window is about timing, not shortcuts.
• Estimated tax deadlines create real urgency for high-income households.
• Every move should be modeled before it is executed.

The timeline that drives the work

• Q4 actions are typically anchored to the calendar year end (December 31).
• For calendar-year taxpayers, estimated tax payments follow a four-period schedule. For the 2025 tax year, the IRS lists these due dates: April 15, 2025; June 16, 2025; September 15, 2025; and January 15, 2026. (https://www.irs.gov/publications/p505)
• If a due date falls on a weekend or legal holiday, the deadline shifts to the next business day. (https://www.irs.gov/publications/p505)
• If you file and pay your 2025 return by January 31, 2026, you may not need to make the January 15, 2026 estimated payment. (https://www.irs.gov/publications/p505)

What to review before you act

1. Income timing. Are you deferring or accelerating income in a way that changes your bracket or triggers extra taxes?

2. Deductions and giving. Are charitable or business expenses timed in a way that actually affects the current year?

3. Entity planning. Is your S-corp or business compensation aligned before the year closes?

4. Estimated tax accuracy. Do your payments match your actual income to date?

Decision checklist

• Have I modeled the impact of each move, not just the idea?
• Do I know the exact date the move must happen by?
• Does this decision change cash flow in the next 90 days?
• Am I solving for taxes or for long-term strategy?

Questions to ask your CPA

• Which two moves could materially change my tax picture this year?
• Do my estimated payments line up with actual income?
• What is the single most time-sensitive decision left this quarter?

Related tools

• Year-End Tax Projection
• Estimated Tax Catch-Up
• Tax Optimization
• Cash Flow Index

Next step

Run the Year-End Tax Projection and share the output with your CPA so every decision is grounded in real numbers.

Compliance note

This guide is for planning and coordination only. It does not provide tax or legal advice. Confirm decisions with a qualified professional.

Sources

• IRS: Estimated tax due dates (Individuals FAQ) https://www.irs.gov/publications/p505