Year-End Tax Strategies for Missouri Business Owners: What to Review Before December 31, 2026

If you own a business in Missouri, the weeks before December 31 are some of the most useful on the calendar for tax planning. Once the year closes, many of your options close with it. A handful of decisions made now — timing an equipment purchase, funding a retirement plan, reviewing your entity structure — can meaningfully shape what you owe when you file your 2026 return in the 2027 filing season.

This article is general education, not specific tax, legal, or accounting advice. Every business is different, and the exact numbers, limits, and deadlines that apply to you depend on your entity type, income level, and individual facts. Please confirm current-year figures and deadlines with your CPA or tax preparer, and loop in your financial planner so your business and personal finances are considered together.

Key takeaways

Retirement plan contributions (SEP IRA, SIMPLE IRA, Solo 401(k), cash balance plans) each carry their own setup and funding deadlines — some before year-end, some tied to your filing date.
Section 179 and bonus depreciation generally require that equipment be placed in service, not just ordered, before the deduction applies to this tax year.
Missouri made state-level tax law changes effective January 1, 2026, so assumptions from prior years may already be outdated.
Estimated tax payments and withholding should be checked against your actual full-year income to avoid underpayment penalties.
No single move fixes everything. Coordinated planning across income timing, deductions, and retirement contributions tends to matter more than any one tactic.

Retirement plan contributions for business owners

Retirement plans remain one of the more powerful year-end levers available to business owners, largely because they can reduce taxable income while also building your own long-term savings. A few options commonly discussed for business owners include:

SEP IRA, funded by the business, often flexible on timing relative to your tax filing deadline (including extensions).
SIMPLE IRA, generally requires the plan to have been established earlier in the year, with contribution rules of its own.
Solo 401(k), useful for owner-only businesses; some year-end planning guidance specifically notes a December 31 deadline for certain plan actions, so this is one to confirm early rather than late.
Cash balance plans, a more advanced defined-benefit style option that can allow for larger contributions for owners further along in their careers, but these require more lead time and actuarial work to set up properly.

Contribution limits change from year to year, and the rules differ meaningfully by plan type. Rather than stating a specific dollar figure here, the better move is to confirm current 2026 limits and deadlines directly with your tax professional or plan administrator before assuming a plan is still open to you.

Entity-level considerations and timing of income and expenses

How your business is structured — sole proprietorship, S corporation, partnership, or C corporation — affects which year-end strategies are even available to you. Two ideas worth discussing with your CPA:

Timing income and expenses. Depending on your accounting method, there may be opportunities to accelerate deductible expenses into this year or defer certain income into next year. This is not automatic, and whether it helps depends on your specific accounting method and current versus expected future tax brackets.
Pass-through entity tax (PTE/PTET) elections. Some businesses structured as pass-throughs may have the option to elect into a state-level entity tax that can affect federal and state tax exposure. This is an election-based strategy, not an automatic deduction, and its availability and benefit depend on your entity type and Missouri's specific rules. It is worth a direct conversation with your CPA rather than assuming it applies to you.

Missouri also made state tax law changes effective January 1, 2026, according to Anders CPA's coverage of 2026 Missouri tax law changes for businesses (opens in a new tab). If you have not reviewed how those changes affect your business specifically, that is a good year-end conversation to have.

Section 179 and bonus depreciation: timing matters

If you have been considering equipment purchases — computers, machinery, vehicles, or other qualifying business property — the timing of when that equipment is placed in service (not simply ordered or invoiced) generally determines which tax year the deduction applies to. This is a common point of confusion: ordering equipment before year-end is not the same as having it in service and usable in your business before year-end.

Exact deduction limits and eligibility rules for Section 179 and bonus depreciation should be confirmed with your tax preparer against current-year IRS guidance before you finalize a purchase decision based on tax benefit alone.

The Qualified Business Income (QBI) deduction

Many owners of pass-through businesses — sole proprietorships, partnerships, and S corporations — may be eligible for a deduction related to qualified business income under Section 199A. Whether you qualify, and how much of a benefit it provides, depends on your taxable income, business type, and wage or capital details specific to your situation. This is another area where a general conversation with your CPA before year-end is more useful than a generic checklist item.

Health Savings Accounts

If your business offers a high-deductible health plan, contributing to a Health Savings Account before year-end can be worth reviewing. HSAs offer a combination of tax advantages that can support both current tax planning and longer-term healthcare savings. As with retirement plans, contribution limits and eligibility rules should be confirmed for the current year rather than assumed from a prior year.

Charitable giving strategies

For business owners who are charitably inclined, year-end is a natural time to review giving strategies such as donor-advised funds, which allow you to make a contribution and decide on specific grants later, or, for those of eligible age with IRA assets, qualified charitable distributions. These strategies interact with both your personal and business tax picture, so they are best reviewed alongside your overall plan rather than in isolation.

Estimated tax payments and avoiding underpayment penalties

Before the year closes, it is worth comparing your actual year-to-date income against what you projected when you set your estimated tax payments. If your business had a stronger (or weaker) year than expected, adjusting your final estimated payment can help you avoid an underpayment penalty when you file. This is also a good time to check withholding on any wages you pay yourself if your business is structured as an S corporation.

Missouri's Department of Revenue maintains its own business tax filing information and tax calendar (opens in a new tab), which is the right starting point for confirming Missouri-specific filing deadlines and requirements rather than relying on general national checklists.

Common mistakes to avoid

Assuming that ordering equipment is the same as placing it in service for depreciation purposes.
Treating entity structure or PTE elections as a one-size-fits-all solution rather than a decision that depends on your specific numbers.
Waiting until tax filing season to think about retirement contributions that may have earlier deadlines.
Assuming prepaying expenses automatically creates a deduction this year without checking your accounting method.
Relying on a single tax move instead of reviewing income projections, estimated payments, retirement contributions, and deductions together.
Assuming prior-year Missouri tax rules still apply without confirming this year's changes.

When to talk with us

Year-end tax planning works best when it is not done in isolation from the rest of your financial picture. At Behrend Wealth Management, we take a holistic view of your financial life, looking at how your business decisions, retirement savings, and personal goals fit together, rather than treating tax planning as a stand-alone task. If you would like a second set of eyes on your year-end strategy alongside your CPA, schedule a call with us before the year closes.

Schedule a call

Frequently asked questions

Do I need to place equipment in service before year-end to claim a deduction this year?

Generally, yes — the equipment typically needs to be placed in service, not just ordered or purchased, for the deduction to apply to this tax year. Confirm the specific rules with your tax preparer.

Can I still open a retirement plan for my business this late in the year?

It depends on the plan type. Some plans have earlier setup deadlines, while others (like a SEP IRA in some cases) may allow more flexibility. Confirm with your tax professional or plan administrator before assuming a plan is still available to you.

Is the pass-through entity tax election right for my business?

It depends on your entity type, income, and state tax exposure. It is an election, not an automatic deduction, so it is worth a specific conversation with your CPA.

What happens if I underpay my estimated taxes?

You may owe an underpayment penalty. Reviewing your year-to-date income against your estimated payments before year-end can help you catch and correct a shortfall.

Did Missouri change any tax rules for 2026?

Missouri made state-level tax law changes effective January 1, 2026. Confirm with your CPA how these changes may affect your specific business.

Should I prepay expenses before year-end to get a deduction?

It depends on your accounting method and specific facts. Prepaying does not automatically create a deduction in every case.

Where can I find Missouri's official business tax filing deadlines?

The Missouri Department of Revenue maintains a business tax page and tax calendar (opens in a new tab) with filing deadline information.

Do I need both a CPA and a financial planner for year-end planning?

They serve different but complementary roles. Your CPA handles tax preparation and filing specifics, while a financial planner helps coordinate those decisions with your broader financial goals.

What is a cash balance plan and is it right for my business?

It is a defined-benefit style retirement plan that can allow for larger contributions for some business owners, but it requires more setup time and actuarial involvement. It is not right for every business.

When are individual and corporate income tax returns due for the 2026 tax year?

Returns for the 2026 tax year are generally filed in the 2027 filing season. Confirm exact due dates with your tax preparer or the Missouri Department of Revenue closer to filing time.