Every year, the same pattern plays out: business owners spend January scrambling to find deductions that needed to happen in December. By the time your tax preparer opens your file, most of the year’s planning opportunities have already closed. Q4 is the last window where decisions still change your outcome — not just your paperwork.

Here’s what actually deserves your attention before December 31st, in the order it’s worth tackling.

Estimate Your Full-Year Income Now

You can’t plan around a number you haven’t calculated. Pull together your actual income through Q3 and a realistic projection for Q4. This single step determines almost everything else on this list — whether accelerating expenses makes sense, whether you’re close to a bracket threshold, and whether your quarterly estimates are still accurate.

Time Equipment and Asset Purchases Deliberately

If you were already planning to buy equipment, software, or vehicles in the next few months, moving that purchase into this fiscal year — or deliberately pushing it into the next one — can meaningfully shift your tax bill through Section 179 and bonus depreciation. The key word is deliberately: never buy something you don’t need purely for a deduction. The math only works if the purchase was coming anyway.

Revisit Your Retirement Contributions

Business owners routinely under-contribute to retirement accounts simply because nobody flagged the deadline. Depending on your entity structure, a SEP IRA, Solo 401(k), or defined benefit plan can shelter a significant amount of income — and several of these have contribution deadlines that extend past year-end, but only if the plan itself is established before December 31st.

The plans that save the most money are the ones you open before the year ends, even if you fund them later.

Check Your Entity Structure Against This Year’s Numbers

An S-corp election that made sense at $400K in revenue might not be optimal at $900K, and vice versa. Q4 is the right time to model next year’s structure against this year’s actuals, because most elections need to be made early in the following year to apply retroactively.

Reconcile Your Books Before You Meet Your Accountant

Nothing wastes more time in a year-end planning meeting than discovering your books aren’t reconciled yet. Clean, current books are what let a planning conversation actually be about strategy instead of data cleanup.

A Simple Way to Prioritize

  • If you have variable income, start with your full-year estimate — everything else depends on it.
  • If you’re close to a revenue milestone, revisit your entity structure before anything else.
  • If your books aren’t current, get them reconciled first so every other decision is based on real numbers.

The Bottom Line

Tax planning that happens in Q4 is worth more than tax preparation that happens in April, because only one of those still has decisions left to make. If you haven’t had a planning conversation with your advisor since last tax season, that’s the actual deadline that matters right now.