2026 Year-End Tax Planning Checklist for Small Business Owners: What to Do Before December 31

Why the calendar matters more than the return

The filing deadline is when the result is reported. December 31 is when most of it is determined. A business owner who starts planning in March is choosing among a much smaller set of options than one who starts in October, and the difference is not marginal.

Below is the 2026 figure set, followed by the decisions each one drives.

The deductions that are now permanent

The One Big Beautiful Bill Act removed the sunsets that made long-range planning difficult. Two provisions matter most to owner-operated businesses.

The qualified business income deduction is permanent at 20%. Rev. Proc. 2025-32 sets the 2026 threshold at $201,750 for single and head of household filers, $201,775 for married filing separately, and $403,500 for married filing jointly. Below the threshold, the calculation is straightforward. Above it, the phase-in range widened for 2026 to $75,000 for single filers and $150,000 for joint filers, up from $50,000 and $100,000. That widening is a quiet benefit: owners caught in the range keep more of the deduction than they would have under prior law. A new floor also applies, guaranteeing a minimum $400 deduction to an active owner with at least $1,000 of qualified business income.

The threshold is measured on taxable income, not business profit. That is the planning hook. Deferring income, accelerating a deduction, or funding a retirement plan can move taxable income below the threshold, and for a specified service business, such as accounting, law, consulting, or health, the entire deduction is at stake across that range rather than just the wage limitation.

One hundred percent bonus depreciation is permanent for qualifying property acquired after January 19, 2025. Section 179 is the alternative route, with a 2026 limit of $2,560,000, a phase-out starting at $4,090,000 of property placed in service, and a separate $32,000 cap for heavy SUVs.

The year-end checklist

Equipment and fixed assets. The test is placed in service, not ordered or paid for. Equipment delivered on December 28 and running qualifies. Equipment paid for in December and delivered in January does not. This timing rule also applies to entity formation decisions-an entity must exist before year-end to claim certain deductions. Section 179 is capped at taxable business income with an indefinite carryforward; bonus depreciation is not, and can create a loss.

Retirement plans. The 2026 employee deferral limit is $24,500, with an $8,000 catch-up at age 50 and up, and $11,250 for those aged 60 through 63. The SEP and overall defined contribution limit is $72,000. Deadlines differ and this is where owners lose the deduction: a solo 401(k) must generally be established by December 31, 2026 to accept 2026 employee deferrals, while a SEP can be established and funded as late as the extended due date of the return.

Income and expense timing. For cash-basis businesses, deferring December invoicing into January and prepaying deductible January expenses in December both work, within limits. The prepayment has to buy something the business actually uses, and the twelve-month rule caps how far forward a prepaid benefit can extend.

State and local taxes. The 2026 SALT cap is $40,400, or $20,200 for married filing separately. It phases down by 30 cents per dollar of modified adjusted gross income above $505,000, reaching a $10,000 floor at $606,333. The cap and thresholds rise 1% annually through 2029, then revert to $10,000 in 2030. Most states now permit a pass-through entity tax election, which moves the state income tax deduction to the entity return and outside the individual cap. That election usually has its own deadline and often requires payment before year end.

Entity structure. An S corporation election for the 2026 tax year is due within two months and fifteen days of the start of the year, so December is the month to decide about 2027 rather than 2026. What is still open is reasonable compensation for the current year, which has to be defensible and paid through payroll before the final run.

The point where this advice reverses

The standard year-end article tells owners to spend before December 31. Run the numbers before accepting that.

A deduction returns your marginal rate, not the purchase price. A business in the 24% bracket that spends $50,000 on equipment to avoid tax saves roughly $12,000 and is out $38,000 of cash for an asset it may not have needed. Accelerating deductions also makes sense only if this year's rate is higher than next year's, which is not automatic in a growing business.

Two 2026 items cut against the reflex specifically. The excess business loss limitation, made permanent by the One Big Beautiful Bill Act, restricts how much net business loss a noncorporate taxpayer can use against other income, and the 2026 thresholds moved down rather than up, to $256,000 for single filers and $512,000 for joint filers. Aggressive acceleration in a loss year can run into that ceiling, and the disallowed amount becomes a carryforward rather than a current saving. Separately, employer-provided meals became fully nondeductible on January 1, 2026 under Section 274(o), so any budgeting that still assumed a 50% deduction on staff meals is overstating the after-tax benefit.

The practical takeaway

Year-end planning is a sequencing exercise, not a shopping list. The order that works is: project taxable income first, locate it against the QBI threshold, then decide whether accelerating or deferring helps, and only then choose between Section 179 and bonus depreciation on any purchase the business was going to make anyway.

Rakesh Jain, CPA PC builds that projection in the fourth quarter, while the decisions are still live. Tax planning services delivered after December 31 are reporting, not planning.

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