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.
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significantly compared to earlier guidance that had bonus depreciation phasing down to 20% in 2026 — those figures are out of date.
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.
Solo 401(k) employee deferral: $24,500 in 2026 ($32,500 if age 50+, $35,750 if age 60–63). Deadline: elect by December 31, 2026 in an existing plan; a sole proprietor with no employees adopting a first plan by April 15, 2027 can still defer for 2026.
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, S-Corp owners need the Solo 401(k) plan document in place by December 31 to make 2026 employee deferrals, even though they can fund it later; a sole proprietor with no employees adopting a first plan has until April 15, 2027. Second, beginning in 2026, if your prior-year FICA wages exceeded $150,000, 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.
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 — for an S-Corp owner the plan itself must exist by December 31, so a plan set up in February 2027 only allows 2027 deferrals. A sole proprietor with no employees opening a first plan has until April 15, 2027.
- 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 $690 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
January 15, 2027: Q4 2026 estimated tax payment.
February 1, 2027 (January 31 is a Sunday): 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. First Solo 401(k) adopted by a sole proprietor with no employees.
Frequently asked questions
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.
No — bonus depreciation was restored to 100% by the One Big Beautiful Bill Act for property acquired 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.
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.
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.
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: in an existing plan they must be elected by December 31, while a sole proprietor with no employees adopting a first plan can make 2026 deferrals until April 15, 2027.
Form 1099-NEC must be filed with the IRS and provided to recipients by February 1, 2027 for the 2026 tax year (January 31 falls on a Sunday). Late filing penalties range from $60 to $340 per form depending on how late, and $690 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.
Yes — unless you file Form 1040 and pay the full balance by February 1, 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.
