Year-End Tax Planning for Small Business Owners: What to Do Before December 31
Tax Planning
The moves that still count for this year, the deadlines that matter, and what to do before December 31.
Quick Answer
What should small business owners do for taxes before December 31?
Before December 31, small business owners should get their books current, project their profit for the year, and decide which tax moves make sense while there's still time to act. Common year-end moves include timing income and expenses, placing needed equipment in service, and making retirement contributions. S corp owners should also finalize their salary, health insurance reporting, and expense reimbursements before the last payroll of the year. Most of these moves can't be made after the year ends.
By the time you sit down to file your tax return, the year is over, and most of the decisions that shaped your tax bill have already been made. That's why the last few months of the year matter so much.
Year-end tax planning is about making decisions while you can still change the outcome. Once December 31 passes, your options narrow to what can still be done at filing time, and for most small business owners, that's not much.
This guide walks through the planning moves worth reviewing before the year closes, from getting a clear read on your numbers to equipment purchases, retirement contributions, S corp payroll, and the deadlines that follow in January.
Start With an Accurate Picture of Your Year
Every good year-end decision depends on knowing where you actually stand. Before you think about buying equipment or making a big retirement contribution, you need a reliable estimate of your profit for the year.
That starts with current books. If your accounts aren't reconciled through at least September or October, that's the first thing to fix. Planning off of incomplete or miscategorized numbers can lead you to spend money chasing deductions you don't need, or to miss a tax bill you didn't see coming.
- Reconcile bank and credit card accounts through the most recent month
- Review your profit and loss statement for miscategorized or missing transactions
- Project the rest of the year based on your normal revenue and expenses
- Compare your estimated tax liability to the estimated payments and withholding you've made so far
With a projection in hand, you can see whether you're heading toward a large balance due, whether your estimated payments are on track, and how much room you have to act.
"The best year-end tax strategy in the world won't help if it's built on numbers you can't trust."
Timing Income and Expenses
If your business uses the cash method of accounting, as most small businesses do, income generally counts in the year you receive it and expenses count in the year you pay them. That gives you some flexibility at year-end.
If you expect to be in a similar or lower tax bracket next year, it can make sense to pay deductible expenses before December 31, such as supplies you'll need in January, annual software subscriptions, or professional fees. On the income side, some businesses can reasonably time invoicing near year-end so payment arrives in January.
There are limits. Prepaying expenses far into the future generally doesn't qualify for a current deduction, and you shouldn't delay collecting money your business actually needs. And if you expect significantly higher income next year, the math may point the other direction: accelerating income into this year while your rate is lower.
The point isn't to shift everything around. It's to make deliberate choices about timing once you know your projected numbers.
Equipment and Vehicle Purchases
Under current law, many businesses can deduct the full cost of qualifying equipment, machinery, furniture, computers, and certain vehicles in the year the property is placed in service, through Section 179 expensing or bonus depreciation, rather than spreading the deduction over several years.
Two details matter here. First, the property has to be placed in service by December 31, meaning it's delivered, set up, and ready to use in your business. Ordering a truck in December that arrives in February won't produce a deduction this year. Second, vehicles have their own rules, and the deduction available depends heavily on the vehicle's weight and how much you use it for business.
Before making a year-end purchase for the deduction, ask:
- Would I buy this if there were no tax benefit?
- Can the business afford the cash outlay or financing payments?
- Will it be delivered and in use before December 31?
- Would a full deduction this year be more valuable than spreading it out over future years?
A deduction saves you a percentage of what you spend, not the whole amount. Spending $50,000 to save roughly $12,000 to $18,000 in tax only makes sense if the business needed the equipment anyway. For more on this decision, see our post on leasing vs. buying equipment.
Retirement Contributions
Retirement contributions are one of the few planning tools that lower your tax bill while the money stays yours. For business owners, they're often the single most effective year-end move.
The deadlines depend on the type of plan and how your business is structured, so it's worth sorting out well before December.
Solo 401(k) plans allow both employee deferrals and employer contributions, which can let owners put away significantly more than many other plan types. If you're an S corp owner, your employee deferrals generally need to run through payroll by the end of the year, so waiting until you file your return to decide is usually too late.
SEP-IRAs are simpler and can generally be established and funded up to your tax filing deadline, including extensions. That makes them a useful fallback, though they don't allow the same employee deferrals a Solo 401(k) does.
For S corp owners, remember that retirement contributions are based on W-2 wages, not distributions. Your salary level directly affects how much you can contribute. Our post on SEP-IRA vs. Solo 401(k) compares the two plans in more detail.
Year-End Checklist for S Corp Owners
S corporation owners have a few items that need to be handled through payroll before the last payroll of the year runs. Once W-2s are prepared, fixing these gets complicated.
Review your reasonable compensation
Look at the salary you've paid yourself this year against the work you performed and the company's profit. If your salary is too low relative to your role and the distributions you've taken, year-end is the time to adjust it, not after the return is filed. Our post on S corp salary vs. distributions covers how to think about the split.
Add health insurance to your W-2
For owners holding more than 2% of the company, health insurance premiums paid by the S corp need to be reported as wages on your W-2. If this isn't handled before year-end payroll closes, you risk losing or complicating the deduction.
Submit accountable plan reimbursements
If you use your home office, personal vehicle, or personal phone for business, an accountable plan lets the S corp reimburse you for those costs tax-free. Submit your mileage logs and expense reports and get reimbursed before December 31.
Check your basis before taking distributions
Year-end distributions should be supported by profit, cash, and your basis in the company. Distributions in excess of basis are generally taxable. See our post on shareholder basis for how this works.
Get Ready for 1099s and W-2s Now
January is a busy month for payroll and information reporting, and the deadlines come quickly after the holidays. Getting organized now saves a scramble later.
Make sure you have a current Form W-9 on file for every contractor you paid this year, and review your vendor payments to identify who will need a 1099-NEC or 1099-MISC. Beginning with payments made in 2026, the general reporting threshold for these forms increased from $600 to $2,000, so some vendors who needed a 1099 in prior years may not need one now. Collecting missing W-9s in January, when contractors are slow to respond, is one of the most common year-end headaches. Our post on preparing for 1099 season walks through the full process.
Key Dates to Keep in Mind
Year-End and Early-2027 Deadlines
The W-2 and 1099-NEC deadline normally falls on January 31. Because that date lands on a Sunday in 2027, the deadline moves to the next business day.
Common Year-End Mistakes
Buying things just for the deduction
A dollar spent to save thirty cents is still seventy cents gone. Purchases should make sense for the business first.
Waiting until the last week of December
Many of the most valuable moves, like payroll adjustments, retirement plan setup, and equipment delivery, take time to arrange. By the week between Christmas and New Year's, vendors are closed, payroll cutoffs have passed, and options are limited.
Forgetting about cash flow
Aggressive year-end spending can leave the business short in January, right when estimated taxes, payroll taxes, and annual renewals come due.
Planning without your tax advisor
Every move on this list interacts with the others. A large equipment deduction might change how valuable a retirement contribution is, or affect your qualified business income deduction. Looking at the full picture together usually leads to better decisions than making each one in isolation.
"The best time to plan for this year's taxes is before the year is over. The second best time is right now."
How Latitude Approaches Year-End Planning
At Latitude Tax Advisors, year-end planning is part of charting the course ahead. We start with your actual numbers, project where the year is heading, and walk through the moves that make sense for your business, not a generic checklist.
That means reviewing your books, your S corp payroll, your retirement options, and any major purchases you're considering, then helping you decide what to do before December 31 and what can wait. The goal is simple: no surprises in April, and a clear plan for the year ahead.
Want to make the most of the rest of this year? Latitude Tax Advisors works with small business owners to plan ahead, keep more of what they earn, and start the new year with confidence.
Frequently Asked Questions
When should small business owners start year-end tax planning?
Ideally in October or early November. That leaves time to get your books current, project your income, and make changes to payroll, retirement plans, or purchases before the year closes.
Do I have to pay for equipment by December 31 to deduct it this year?
What generally matters is that the equipment is placed in service, meaning ready and available for use in your business, by December 31. Equipment that is financed can still qualify, but equipment that arrives after year-end generally won't produce a deduction for this year.
Can I still open a retirement plan after the year ends?
Some plans, like a SEP-IRA, can generally be set up and funded up to your filing deadline, including extensions. Other plans have earlier deadlines, and S corp owners generally need salary deferrals to run through payroll before year-end.
What should S corp owners do before the last payroll of the year?
Review your reasonable compensation, make sure health insurance premiums for owners with more than 2% of the company are added to your W-2, process any retirement deferrals, and submit accountable plan reimbursements.
When is the Q4 estimated tax payment due?
For the 2026 tax year, the fourth-quarter estimated payment is due January 15, 2027.
This article is for informational purposes only and does not constitute legal or tax advice. Consult a qualified professional for guidance specific to your situation.
