Year-End Tax Planning for High-Income Earners: What Should You Review Before December 31?

By October, many taxpayers have a clearer picture of their annual earnings, investment activity, and major financial decisions. Yet there is still time to influence how some of those items affect their 2026 tax liability.

For high-income professionals and business owners, year-end planning should begin with a projected tax calculation, not a list of deductions.

Here are the areas worth reviewing before December 31.

1. Has your income changed significantly this year?

Bonuses, equity compensation, business profits, capital gains, and investment income can push taxable income substantially above initial expectations.

Start by projecting your full-year income, including amounts from businesses and investments that may not appear on a regular paycheck.

That projection can reveal exposure to higher marginal tax rates, the 3.8% Net Investment Income Tax, additional Medicare tax, and income-based deduction limitations.

It also provides the foundation for evaluating whether accelerating or deferring certain income and expenses would actually produce a tax benefit.

2. Are you making the most of available deductions?

The federal state and local tax (SALT) deduction limit for 2026 is generally $40,400, subject to an income-based reduction beginning at $505,000 of modified adjusted gross income for most filing statuses.

For higher-income taxpayers, that reduction can substantially limit the benefit. The interaction between state taxes, mortgage interest, charitable contributions, and other itemized deductions deserves closer attention.

Charitable giving also has new considerations in 2026. Taxpayers who itemize generally face a 0.5% adjusted gross income threshold before charitable contributions become deductible, along with additional limitations affecting taxpayers in the highest federal tax bracket.

Timing and structuring contributions may therefore matter, particularly for individuals making substantial gifts.

3. Have you reviewed capital gains and investment losses?

Investment activity can materially affect a high-income taxpayer's year-end liability.

Review realized gains and losses, potential tax-loss harvesting opportunities, and any anticipated investment sales.

Capital losses may offset capital gains, subject to applicable rules. However, wash-sale restrictions and the economic merits of each transaction should be considered before making trades solely for tax purposes.

Investors with concentrated stock positions, private investments, or significant deferred gains may need a more coordinated review.

For example, investors with outstanding deferred gains from Qualified Opportunity Fund investments generally face mandatory gain recognition on December 31, 2026, even if they continue holding the investment.

4. Are your retirement contributions and compensation elections optimized?

Review employer-sponsored retirement contributions, available catch-up contributions, and any remaining opportunities to make eligible contributions before year-end.

For 2026, certain higher-income employees making catch-up contributions to workplace retirement plans are subject to new Roth contribution requirements. This can change the expected current-year tax benefit.

Business owners should also consider retirement-plan contributions alongside compensation, business profitability, and cash flow.

The appropriate strategy depends on plan eligibility, contribution limits, and the individual's broader financial circumstances.

5. Have business income and personal taxes been evaluated together?

For owners of pass-through businesses, personal tax planning cannot be separated from business performance.

Year-end business decisions involving equipment purchases, depreciation, compensation, retirement contributions, and deductible expenses may affect the owner's individual tax liability.

Eligible businesses may also benefit from current depreciation provisions, but purchasing an asset solely to generate a deduction is rarely sound financial planning.

The objective should be to evaluate the tax consequences of legitimate business decisions while preserving the company's liquidity and operating flexibility.

6. Are your withholding and estimated payments sufficient?

Even when an effective tax strategy reduces total liability, inadequate payments throughout the year can create penalties and an unexpected balance due.

Compare projected federal and state liabilities against withholding, estimated payments, and available credits.

This is particularly important for taxpayers receiving bonuses, investment gains, partnership income, or other amounts without sufficient withholding.

The fourth federal estimated-tax payment for 2026 is generally due January 15, 2027. However, making that payment does not automatically eliminate penalties associated with earlier underpayments.

Reviewing payment requirements now allows more time to address potential shortfalls.

What should happen before December 31?

The most effective year-end review brings these decisions together.

A deduction may be less valuable than expected because of an income limitation. A capital loss may offset a gain, but selling an investment may conflict with a longer-term strategy. A business purchase may reduce taxable income while placing unnecessary pressure on cash reserves.

The goal is not simply to minimize this year's tax bill. It is to make financially sound decisions with a clear understanding of their tax consequences.

For high-income earners, that requires looking beyond individual transactions and evaluating the complete financial picture before the year closes.

At Alinea, we help high-income individuals and business owners navigate complex tax decisions through proactive planning and coordinated financial oversight. Our CPA-led approach connects personal and business tax considerations so clients can make informed decisions throughout the year.

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