Do I need to make 2026 estimated tax payments if my 2025 income spike was a one-time event?

Not necessarily. A big 2025 tax bill does not automatically mean you must make 2026 estimated payments if that income is not repeating. What matters is whether your 2026 withholding and credits will be enough to cover your actual 2026 tax or one of the IRS safe harbor rules.

The IRS generally expects estimated payments only if both of these are true:

• You expect to owe at least $1,000 for 2026 after withholding and refundable credits, and
• Your withholding and credits will be less than the smaller of:
• 90% of your 2026 tax, or
• 100% of your 2025 tax; 110% if your 2025 AGI was over $150,000 ($75,000 if married filing separately)

That means tax software can print 2026 vouchers based on your 2025 return even when they are not actually necessary. If your 2025 income spike came from a one-time bonus, stock sale, Roth conversion, business event, or other nonrecurring income, and your 2026 withholding will cover your normal income, you can often ignore the suggested vouchers.

When estimated payments probably are not needed:

• Your 2026 income is going back to normal
• Your W-2 withholding is already enough to cover your expected 2026 tax
• You increase withholding at work instead of sending quarterly estimates

When you still may want to pay estimates:

• Your 2026 income is uneven and you expect another large untaxed event later in the year
• You are self-employed or have side income with little withholding
• You want to rely on the prior-year safe harbor and avoid having to project your 2026 tax exactly

If your income really is lumpy, Publication 505 also allows you to annualize your income on Form 2210 so you are not penalized for uneven earnings. In plain English, you do not have to blindly follow the vouchers. Base your 2026 payments on your expected 2026 tax situation.