Estimated Taxes: Avoiding the Q4 Surprise

Estimated tax payments made earlier in the year are based on what you expected your financial picture to look like. By the end of Q3, reality may look very different.

Perhaps your business had a stronger year than anticipated. You received a large bonus, sold appreciated investments, exercised stock options or generated additional income from real estate or other investments. Any of these developments can change your projected tax liability.

That makes the transition from Q3 to Q4 an important time to revisit your numbers rather than discovering the difference when your tax return is prepared next spring.

Why Your Original Estimate May No Longer Work

The federal tax system generally operates on a pay-as-you-go basis. For investors and business owners whose income is not fully covered by withholding, that often means making estimated tax payments throughout the year.

The challenge is that variable income can make those estimates a moving target.

A business owner who projected $500,000 of income in January, for example, may be on track for considerably more by September. An investor may have realized an unexpected capital gain. An executive could receive a bonus that pushes household income higher than originally anticipated.

Even when income rises significantly, deductions, business expenses and investment losses may have changed as well. The goal is not simply to look at how much you earned. It is to update the complete tax projection.

Use Q3 as a Tax Planning Checkpoint

Before heading into the final months of the year, review year-to-date income and compare it with the assumptions used to calculate previous estimated payments. This is also an opportunity to project what could happen between now and December 31.

For 2026, the third estimated federal tax payment is due September 15, while the fourth payment is generally due January 15, 2027. Depending on your circumstances, adjusting upcoming payments or withholding may help address a projected shortfall.

Higher-income taxpayers should also pay particular attention to estimated tax safe-harbor rules. In many cases, avoiding an underpayment penalty requires paying at least 90% of the current year’s tax liability or, for taxpayers above certain income thresholds, 110% of the prior year’s tax liability.

Turn the Tax Projection Into a Planning Opportunity

Updating estimated taxes can reveal opportunities beyond simply determining how much to send to the IRS.

If income is significantly higher than expected, there may still be time to evaluate retirement plan contributions, business expenditures, charitable strategies, tax-loss harvesting and other year-end planning decisions. The appropriate strategy depends on your broader financial situation rather than any single tax-saving opportunity.

For business owners and high-net-worth investors, the objective should be to enter Q4 with a clearer understanding of where the year is headed.

At Illumination Wealth, we help clients coordinate tax planning with investments, business decisions and long-term wealth management. Revisiting your tax projection before year-end can reduce surprises while giving you more time to make thoughtful financial decisions. For help with all your year-end tax planning, contact Illumination Wealth today.