Tax Filing
May 30, 2026

Year-End Tax Planning Checklist for Small Business Owners (2026)

Year-End Tax Planning Checklist for Small Business Owners (2026)
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Why year-end planning still matters in November and December

Most of your 2026 tax bill is locked in by what already happened — revenue booked, salary paid, entity chosen. But the last six weeks of the year still hold real leverage. Place equipment in service before December 31 and you can deduct it now instead of over five or seven years. Fund a Solo 401(k) and you cut taxable income by tens of thousands. Miss the W-9 collection window and you walk into 1099 season chasing contractors who won't return your calls.

This checklist covers 12 actions that move the needle for small business owners earning $50,000 to $5 million. Each item lists what to do, the deadline, and the 2026 dollar figure tied to it.

The 12 year-end actions that matter

Run this list in November so you have time to act. Some items have hard December 31 deadlines. Others stretch into 2027 but only if you've set them up correctly during 2026.

1
Place equipment in service by December 31
Section 179 lets you expense up to $2,560,000 of qualifying equipment in 2026. Bonus depreciation is back to 100% for property placed in service after January 19, 2025. Ordering it doesn't count — it has to be installed and ready for use.
2
Open a Solo 401(k) by December 31 if you don't have one
The plan must exist by December 31 to defer 2026 employee contributions. Funding can wait until your tax filing deadline including extensions, but the plan document needs a 2026 effective date.
3
Run S-Corp owner payroll before year-end
If you're an S-Corp owner who hasn't paid yourself reasonable W-2 wages, you have until December 31 to fix it. Wages cannot be backdated into a prior year through a January payroll run.
4
Collect W-9s from every contractor paid $600+
You'll need each contractor's legal name, address, and TIN to file Form 1099-NEC by January 31, 2027. Contractors paid by credit card or PayPal Goods & Services don't need a 1099-NEC — those are reported on Form 1099-K.
5
Max out your HSA
For 2026, the limit is $4,400 self-only or $8,750 family, plus $1,000 catch-up at age 55+. You can contribute through April 15, 2027, but only if you were enrolled in a qualifying HDHP during 2026.
6
Pay your Q4 estimated taxes by January 15, 2027
Underpayment of estimates triggers Form 2210 penalties. Pay at least 100% of your 2025 liability (110% if 2025 AGI exceeded $150,000) or 90% of 2026 to avoid the penalty.
7
Decide whether to accelerate or defer income
Higher 2027 bracket expected? Pull December invoices into 2026. Lower 2027 expected? Push them into January.
8
Prepay Q1 2027 expenses you'll owe anyway
Cash-basis taxpayers can pull 2027 deductions into 2026 by prepaying January rent, software, or insurance in December. The 12-month rule generally limits prepayments to 12 months out and not past the end of the next tax year.
9
Review your QBI deduction position
For 2026, the QBI phase-in starts at $201,775 single / $403,500 married filing jointly. If you're close to those thresholds, every dollar of additional deduction matters because it can preserve your full 20% QBI write-off.
10
Time long-term capital gains carefully
If you're selling business assets or investments, holding them for more than 365 days qualifies the gain for long-term capital gains rates (0%, 15%, or 20%) instead of ordinary rates that can hit 37%. Check your purchase dates before year-end.
11
Reconcile your books before December 31
If your books are a mess in late December, you can't tell whether to accelerate or defer. Reconcile bank accounts, categorize transactions, and tie out loan balances. Clean books in November are worth more than clever planning in March.
12
Document business mileage and home office
The 2026 standard mileage rate is 72.5¢ per business mile. Pull together your mileage log now — reconstructing it in March from credit card statements rarely survives an audit.

Equipment purchases and Section 179

Section 179 is the biggest year-end lever for businesses that need new equipment. It lets you expense up to $2,560,000 of qualifying property in 2026 instead of depreciating it over years. The deduction starts phasing out dollar-for-dollar once your total qualifying purchases exceed $4,090,000.

Bonus depreciation is back to 100% for property acquired and placed in service after January 19, 2025, under the One Big Beautiful Bill Act. That changes the math significantly compared to earlier guidance that had bonus depreciation phasing down to 20% in 2026 — those figures are out of date.

"Placed in service" is the trigger, not the order date
The IRS rule is clear: equipment must be ready and available for its intended use by December 31. Ordering a $40,000 CNC machine in November doesn't qualify if it's still on a truck on January 3. Take delivery, install, and turn it on before year-end.

Vehicles have stricter rules. Heavy SUVs (gross vehicle weight 6,000–14,000 lbs) carry a special Section 179 cap of $32,000 for 2026. Trucks and vans over 14,000 lbs are generally treated like equipment.

Retirement contributions: SEP-IRA, Solo 401(k), and HSA

Retirement and HSA contributions are the cleanest tax reduction tool a self-employed business owner has. They convert taxable income into deferred or tax-free savings without changing what you do. The 2026 limits are higher than 2025, and the deadlines aren't all the same.

2026 contribution limits and deadlines
SEP-IRA: Up to 25% of net self-employment income, capped at $72,000. Deadline: tax filing deadline including extensions (October 15, 2027 for sole props on extension).
Solo 401(k) employee deferral: $24,500 in 2026 ($32,500 if age 50+, $35,750 if age 60–63). Deadline: December 31, 2026 — but the plan must exist by then.
Solo 401(k) employer profit-share: Up to 25% of compensation, combined annual additions cap of $72,000 ($80,000 at 50+, $83,250 at 60–63). Deadline: tax filing deadline including extensions.
HSA: $4,400 self-only / $8,750 family, plus $1,000 catch-up at 55+. Deadline: April 15, 2027.
Traditional IRA: $7,500 ($8,600 at 50+). Deadline: April 15, 2027.

Two practical points. First, the Solo 401(k) plan document has to be in place by December 31 to make 2026 employee deferrals — even though you can fund it later. Second, beginning in 2026, if your prior-year FICA wages exceeded $145,000, your 401(k) catch-up contributions (age 50+) must be made on a Roth basis under SECURE Act 2.0.

Income and deduction timing

Cash-basis taxpayers — most small businesses — recognize income when received and expenses when paid. That gives you a window in late December to push items in or out of 2026. Accelerate income if you expect higher rates in 2027 or want to use expiring NOL carryforwards. Defer income if 2026 was unusually high or if extra income would cost you the QBI deduction.

The most common mistake is treating timing as a free win. It isn't. Accelerating $30,000 of income into 2026 only helps if your 2027 marginal rate would have been higher. Run a two-year projection before deciding.

Worked example — buying a $40,000 piece of equipment in December

Sarah runs a Florida LLC taxed as an S-Corp. Her 2026 net income after a reasonable salary is on track for $180,000. She's considering a $40,000 piece of equipment that she'd otherwise buy in March 2027.

Calculation: Buy in December 2026 vs. March 2027
Equipment cost: $40,000
Section 179 deduction (placed in service Dec 2026): $40,000
Federal tax bracket (single, ~$180K income): 24%
Federal tax saved in 2026: $9,600
Self-employment / payroll tax saved: $0 (S-Corp net flows to K-1, not subject to SE tax)
QBI deduction lost on $40K reduction: approximately $1,920 lost benefit ($40K × 20% × 24%)

Net 2026 federal benefit: approximately $7,680

Buying in December accelerates the deduction by one tax year — about $7,680 in 2026 tax saved, then lost on the 2027 return. The real benefit is time value of money plus any rate arbitrage if 2027 would be lower. State tax conformity matters too: many states do not fully follow Section 179 or bonus depreciation.

If you're a foreign owner of a US LLC

Year-end planning for foreign-owned single-member LLCs is different. If your LLC is disregarded and you have no US trade or business, you usually have no federal income tax to plan around. Your priorities are documentation:

  • Form 5472 prep: Track every reportable transaction with you and any related parties — capital contributions, loans, payments. The penalty for missing or incomplete Form 5472 is $25,000 per form.
  • Sales tax nexus: If you're an Amazon FBA seller, FBA inventory in a state can create nexus. Year-end is when sellers discover they should have been registered all year in three more states.

Berik runs a Wyoming LLC from Almaty selling on Amazon FBA. His year-end checklist is mostly documentation: confirming books reconcile to Amazon settlement reports, listing transfers between his personal account and the LLC, and making sure he can complete Form 5472 by April 15, 2027. There's no Section 179 to time and no Solo 401(k) to fund — but missing the 5472 deadline costs him $25,000.

Common mistakes

  • Ordering equipment too late — buying a machine on December 27 that arrives January 8 means no 2026 deduction. The "placed in service" rule is strict.
  • Skipping the Solo 401(k) plan setup — funding has a long deadline, but the plan itself must exist by December 31. Setting up a plan in February 2027 only allows 2027 contributions.
  • Forgetting S-Corp owner payroll — running zero W-2 wages all year then trying to "true up" with a January payroll won't move wages into the prior tax year. The IRS treats reasonable compensation as an annual requirement, not a December scramble.
  • Ignoring W-9 collection — chasing contractors for W-9s in late January is a guaranteed late 1099-NEC filing. Penalties start at $60 per form (within 30 days of the deadline) and rise to $340 per form after August 1, with $680 per form for intentional disregard.
  • Treating timing strategies as free wins — deferring income to 2027 only helps if 2027's bracket is the same or lower. Run the two-year projection before pulling the trigger.

Key deadlines at a glance

Hard year-end deadlines ⚠
December 31, 2026: Equipment placed in service for Section 179. Solo 401(k) plan document executed. S-Corp owner payroll run. Charitable contributions made.
January 15, 2027: Q4 2026 estimated tax payment.
January 31, 2027: Form W-2 to employees. Form 1099-NEC to contractors and IRS.
March 15, 2027: S-Corp (Form 1120-S) and partnership (Form 1065) returns due, or extension via Form 7004.
April 15, 2027: Form 1040, sole prop Schedule C, single-member LLC. Form 5472 (foreign-owned LLCs). HSA and IRA contributions for 2026.

Frequently asked questions

How much can I contribute to retirement as a self-employed business owner in 2026?

A Solo 401(k) allows up to $72,000 total in 2026 ($80,000 at 50+, $83,250 at 60–63), combining the $24,500 employee deferral with employer profit-sharing of up to 25% of compensation. A SEP-IRA is simpler but capped at $72,000 from employer contributions only.

Is bonus depreciation phasing out?

No — bonus depreciation was restored to 100% by the One Big Beautiful Bill Act for property placed in service after January 19, 2025. Earlier guidance showing a phase-down to 20% in 2026 no longer applies. Verify current rules before relying on older sources.

Should I buy equipment just to get a tax deduction?

No. A $40,000 deduction at a 24% bracket saves you $9,600 in tax — but you still spent $40,000. Only buy equipment you actually need. Year-end timing matters when the purchase is already planned for early next year and pulling it forward costs nothing operationally.

What's the difference between Section 179 and bonus depreciation?

Section 179 is elective, capped at $2,560,000 for 2026, and can't exceed your business's taxable income. Bonus depreciation is automatic unless you opt out, has no dollar cap, and can create a net operating loss. The IRS requires Section 179 first, then bonus depreciation on remaining basis.

Can I still fund my SEP-IRA after December 31?

Yes. SEP-IRA contributions for 2026 can be made up to your tax filing deadline including extensions — generally April 15, 2027, or October 15, 2027 with Form 4868. Solo 401(k) employee deferrals are different: those have a December 31 cutoff for self-employed sole proprietors.

When are 1099-NECs due?

Form 1099-NEC must be filed with the IRS and provided to recipients by January 31, 2027 for the 2026 tax year. Late filing penalties range from $60 to $340 per form depending on how late, and $680 per form for intentional disregard. Collect W-9s before year-end so you have the contractor's legal name, address, and TIN ready to file.

Do I need to make a Q4 estimated tax payment if I'll file early?

Yes — unless you file Form 1040 and pay the full balance by January 31, 2027, the Q4 estimated payment is still due January 15, 2027. The safe harbor is 100% of your 2025 liability (110% if 2025 AGI exceeded $150,000) or 90% of 2026.

This article provides general information about US tax topics and is not a substitute for personalized advice from a qualified tax professional. Tax law changes frequently — verify current rules with a tax professional before filing or making decisions based on this content.