Two owners run businesses with identical revenue and identical December profit. One buys equipment in November and puts it to work immediately, tops up a retirement plan through payroll, and reviews owner compensation before the final pay run. The other does none of that and finds out in March that the window has closed.
This guide covers seven small business tax planning strategies worth reviewing before the year ends, the 2026 figures attached to each, and the timing rules that catch owners who wait too long.
Why Timing Decides Your Business Tax Bill
Most business deductions depend on when something happens, not when it is recorded. Equipment must be placed in service. Retirement plans must be adopted. Elections must be filed on time. A December purchase still sitting in a crate in February is generally a next year deduction, and accurate bookkeeping in March will not change that.
That is the practical difference between filing and planning. Useful tax planning for business owners happens in the fourth quarter, when you have a reliable profit estimate and enough runway to act on it.
Strategy 1: Shift Income and Expenses Across December 31
How much control you have depends on your accounting method. A cash basis business recognizes income when it is received or made available, so holding a late December invoice can move that revenue into the next year. An accrual basis business generally recognizes income when the right to it is fixed and the amount determinable, so delaying the paperwork alone does not defer anything.
Constructive receipt limits this either way. A check available to you in December is December income even if you do not deposit it.
On the expense side, the 12 month rule can allow a cash basis business to deduct prepaid items such as insurance, rent, or software in the year paid, provided the applicable requirements are met and the benefit does not extend beyond the allowed period. Not every prepayment qualifies, so review the specific expense before relying on it. Paying by credit card in December is treated as payment.
Strategy 2: Place Equipment in Service Before the Year Closes
The Section 179 deduction for 2026 allows up to $2,560,000 of qualifying property to be expensed immediately, reduced dollar for dollar once total qualifying purchases exceed $4,090,000. Business use must exceed 50 percent, and the deduction cannot exceed your aggregate business taxable income, though disallowed amounts carry forward. Heavy sport utility vehicles carry a separate $32,000 cap.
Bonus depreciation is available at 100 percent for qualifying property acquired and placed in service after January 19, 2025. Unlike Section 179, it is not limited by business income, which makes it the better fit when a large purchase would exceed your profit. Both sit inside broader business tax decisions rather than standing alone.
California does not conform to federal bonus depreciation, and the California Section 179 limit is $25,000 subject to state phaseout rules, so federal and state results can differ significantly. Owners in the Bay Area should model both with a Walnut Creek CPA before committing to a large purchase.
Strategy 3: Fund a Retirement Plan Built for Owners
For a profitable owner run business, this is often the largest remaining lever, and the money stays in your household.
The solo 401(k) contribution limits for 2026 start with a $24,500 elective deferral, plus an $8,000 catch-up at age 50 and $11,250 in the year you turn 60 through 63. The deferral limit applies per person across all plans you participate in. Total employee and employer additions to a defined contribution plan cap at $72,000, and compensation above $360,000 is not counted. Employer contributions to a SEP IRA are capped by the same annual additions limit, and SIMPLE IRA deferrals are limited to $17,000 with a $4,000 catch-up.
Deadlines differ by plan and entity type. The SEP IRA deadline generally runs to the due date of the return including extensions, which makes it the common fallback once December has passed. A SIMPLE IRA generally has to be set up by October 1 of the year it covers. A solo 401(k) can be adopted after year end in some first year situations under SECURE 2.0, but owners taking a W-2 salary from an S corporation generally need a deferral election in place and amounts withheld through payroll during the year.
The HSA contribution limits for 2026 are $4,400 for self only coverage and $8,750 for family coverage, plus a $1,000 catch-up at 55, if you are enrolled in a qualifying high deductible plan. These decisions usually sit alongside broader retirement tax strategy.
Strategy 4: Protect the Qualified Business Income Deduction
The qualified business income deduction under Section 199A is permanent and often worth more than every equipment purchase combined.
For 2026, the taxable income thresholds are $201,750 for single and other filers and $403,500 for joint filers. The QBI deduction phase-in thresholds end at $276,750 for single and other filers and $553,500 for joint filers, and across that range the wage and property limitations apply. Specified service businesses such as consulting, law, health, and accounting practices see the deduction phase down to zero over the same span.
That creates a window closing on December 31. If taxable income sits inside the phase-in range, a retirement contribution or a deferred invoice can recover a deduction worth more than the amount deferred. Non service businesses have the opposite option, since paying additional W-2 wages or placing qualified property in service can raise the limitation ceiling. Proper tax planning services should model the full calculation before you commit to a large December deduction.
Strategy 5: Review Owner Compensation and Entity Structure
S corporation reasonable compensation is not optional. Set it too low and distributions can be reclassified as wages with back payroll taxes and penalties. Set it too high and you overpay Social Security and Medicare while reducing the income eligible for the 199A deduction.
Reviewing this before the final payroll of the year is far simpler than correcting it later, since post year end fixes may involve additional payroll filings or corrected forms depending on the facts.
If a future sale is part of the picture, raise the C corporation question early. The rules around qualified small business stock reward planning that starts years ahead of an exit, not months.
Strategy 6: Consider a Pass-Through Entity Tax Election
The SALT cap for 2026 is $40,400 and it phases down for higher income households. For most California owners, that does not cover actual state tax.
A pass-through entity tax election lets a qualifying S corporation, partnership, or LLC pay California income tax at the entity level at a flat 9.3 percent and deduct it as a business expense, outside the individual cap. SB 132 extended the program through tax years beginning before January 1, 2031.
The timing rules are strict and are not a December decision alone. California requires a prepayment by June 15 of the tax year equal to the greater of $1,000 or 50 percent of the prior year elective tax, and the balance is due by the original due date of the entity return. Current rules also reduce the credit available to owners where required payments are not made as scheduled, so the schedule needs planning well before year end.
Strategy 7: Close the Books and Fix Documentation
Write off equipment that was scrapped or retired, and assess receivables that are genuinely uncollectible. Confirm an accountable plan is documented for mileage and home office reimbursements, since payments made outside a written plan are generally treated as taxable wages. Clean records make this faster, which is where outsourced bookkeeping earns its keep.
The 1099-NEC threshold also changed, rising from $600 to $2,000 for payments made after 2025, so your vendor review needs fresh eyes rather than last year’s list.
Check the estimated tax safe harbor as well. It is generally 100 percent of prior year tax, or 110 percent if prior year adjusted gross income exceeded $150,000, or $75,000 for married filing separately.
An Illustration of What These Moves Can Add Up To
The figures below are a simplified illustration only, not an expected result. They assume a 32 percent federal marginal rate and ignore state tax and other limitations.
| Year-end move | Deduction | Illustrative federal effect at 32 percent |
| Equipment placed in service by December 31 | $60,000 | $19,200 |
| Additional employer retirement contribution | $30,000 | $9,600 |
| Family HSA contribution | $8,750 | $2,800 |
| Prepaid costs meeting the 12 month rule | $12,000 | $3,840 |
| Total | $110,750 | $35,440 |
Actual results differ. Deductions that reduce qualified business income also reduce the 199A deduction calculated on it, and the size of that offset depends on your income level, wage base, and business type. California conformity differences will also change the state outcome on the equipment line.
Mistakes That Undo Good Planning
- Buying equipment purely for the deduction. A $60,000 purchase costs $60,000 in cash to save a fraction of that in tax.
- Missing the in service test. An order or even a delivery in December does not qualify if the asset is not ready and available for use.
- Leaving everything until the return is prepared. Some options remain after year end, including SEP funding and certain elections, but the highest value moves are already gone.
How Capital Tax Can Help
Capital Tax is a CPA firm with over 25 years of experience advising business owners on proactive planning rather than after the fact reporting.
Our team can help you:
- Project 2026 taxable income early enough to act on it
- Compare Section 179 and bonus depreciation for both federal and California purposes
- Review owner compensation before the final payroll of the year
- Select and establish a retirement plan that fits your profit level and deadlines
- Plan pass-through entity tax payments around California’s schedule
- Align business decisions with your individual tax return
- Keep planning on a year round footing through our service packages
Bottom Line
Year-end tax planning is not about finding obscure deductions in December. It is about knowing your numbers early, applying the right 2026 limits to your situation, and completing the steps that no extension can reopen.
To review your position while there is still time to change it, start with a free business health assessment.
Frequently Asked Questions
What is the deadline for year-end tax planning moves?
Many close on December 31, including placing equipment in service and running payroll adjustments. Others extend further, since a SEP IRA can generally be established and funded up to the due date of the return including extensions.
Can I deduct equipment I bought in December but used in January?
Generally no. Both Section 179 and bonus depreciation require the property to be placed in service, meaning ready and available for its intended use, within the tax year.
Do year-end deductions reduce my QBI deduction?
They can. Business deductions lower qualified business income, which affects the 20 percent deduction calculated on it. The size of that effect depends on your taxable income, W-2 wages, and whether the business is a specified service trade or business.
Should I set up an S corporation before December 31?
An S election generally takes effect for the full year only if filed within roughly the first two and a half months of that tax year. An election filed in December usually applies to the following year, unless late election relief is available based on the specific facts.