Dental Practice Year-End Tax Planning Checklist (2026)
Most of your biggest tax-saving moves for 2026 have hard deadlines — December 31 for retirement plan establishment, equipment placed in service, and charitable contributions; January 15, 2027 for Q4 estimated taxes. Miss these and there's no filing-season fix. This checklist organizes every major action by deadline so you can work through it with your CPA before the window closes.
1. Retirement plan contributions
Retirement contributions are the most powerful lever for dental practice owners — a dentist netting $500,000 and age 52 can shelter over $220,000 pre-tax in a single year by combining a Solo 401(k) with a cash balance plan. But the mechanics depend on timing.
Solo 401(k): establish by December 31, fund by tax filing deadline
If you don't already have a Solo 401(k) and you want to shelter income from this tax year, you must establish the plan by December 31, 2026.1 You do not need to fund it by December 31 — contributions can be made up to your tax return filing deadline, including extensions (October 15, 2027 with an extension).
| Action | 2026 limit | Deadline |
|---|---|---|
| Employee elective deferral | $24,500 ($32,500 age 50–59, 64+; $35,750 ages 60–63) | December 31, 2026 (must be elected before year-end) |
| Employer profit-sharing contribution | Up to 25% of W-2 salary (S-corp) or 20% of net SE income (sole prop), combined cap $72,000 | Tax filing deadline (April 15 or Oct 15 with extension) |
| Establish new Solo 401(k) | — | December 31, 2026 |
S-corp dentists: your employee deferral must be withheld from W-2 paychecks issued before December 31. If you realize in late December that you haven't maxed your deferral, you need your payroll provider to process an extra paycheck or a year-end true-up paycheck. Do not wait until after year-end — the election must occur in the tax year.
Sole proprietors: you can elect your deferral at any time up to December 31 by completing a contribution agreement with your plan provider. Some providers have forms that need a few days to process — do this in early December, not Christmas Eve.
Cash balance plan: critical year-end coordination
If you have an existing cash balance plan, your actuary-calculated contribution range must be funded by your tax return filing deadline (including extension). However, December is when you should confirm your target contribution with your actuary and make sure you have the cash set aside.
If you're considering starting a cash balance plan: the establishment deadline is also December 31 of the first contribution year. But cash balance plans require actuarial design — most providers need 4–6 weeks of lead time. If it's October and you haven't started, act now. If it's December 15, it may be too late to establish one for this tax year.
- Solo 401(k) deferral + catch-up: $32,500
- Solo 401(k) employer contribution: ~$47,500
- Cash balance plan (actuarially determined, ~age 52): ~$160,000–$200,000
- Total sheltered: $240,000–$280,000 — all deductible against 2026 income
IRA and Roth IRA: fund by April 15
IRA contributions for 2026 can be made through April 15, 2027 — no extension. The limit is $7,500 per person (no catch-up distinction above age 50 for IRAs — the $1,000 catch-up is included in the $7,500).1 Most dental practice owners earn above the Roth IRA direct contribution phase-out ($242,000–$252,000 MFJ for 2026), so a backdoor Roth conversion is the mechanism.
2. Equipment purchases: place in service by December 31
To claim Section 179 or bonus depreciation on equipment, the asset must be placed in service — actually installed and operational — by December 31. A purchase order signed December 30 doesn't count if the CBCT scanner isn't delivered and working until January 3.
| Rule | 2026 amount | Key constraint |
|---|---|---|
| Section 179 deduction limit | $2,560,0002 | Cannot create a net operating loss (excess carries forward) |
| Bonus depreciation (OBBBA) | 100% of asset cost3 | CAN create a net operating loss; NOL carries forward indefinitely |
| Combined practical result | Full first-year deduction on most dental equipment | Asset must be placed in service by Dec 31, 2026 |
Decision framework for a large equipment purchase: If you've been considering a scanner, laser, or operatory renovation, the tax math is identical whether you buy in December or January — but the deduction year changes. If your 2026 practice income is higher than you expect 2027 income to be (e.g., you're planning to reduce hours or sell the practice), accelerating into 2026 at the higher income level maximizes the value of the deduction. If 2027 will be a higher-income year, defer the purchase.
For the full buy vs. lease vs. loan analysis with worked examples, see the dental equipment financing guide.
3. S-corp payroll: finalize by December 31
If you operate as an S-corp, December is when you review your W-2 salary for reasonableness and make any final payroll adjustments. Two issues come up most often:
Reasonable compensation audit exposure
The IRS requires that S-corp owner-employees pay themselves a "reasonable" W-2 salary for the services they provide. There's no bright-line safe harbor, but the IRS has challenged salaries that are implausibly low relative to practice revenue. If your practice grossed $800,000 and you paid yourself a $60,000 W-2, expect scrutiny.
A common benchmark is that your W-2 salary should approximate what you'd pay a replacement dentist doing the same clinical work — typically $180,000–$350,000 for a general practice owner dentist depending on location and production volume. Your CPA can help you document the reasonable comp determination before year-end.
The 25%-of-W-2 contribution formula
For S-corp dentists, your employer Solo 401(k) profit-sharing contribution is capped at 25% of your W-2 salary. This creates a specific optimization point: at a $190,000 W-2 salary, 25% × $190,000 = $47,500 — which, combined with your $24,500 employee deferral, exactly hits the $72,000 annual addition cap. Salary above $190,000 doesn't add more 401(k) contribution room (but does cost more in FICA). See the owner compensation guide and S-corp calculator for your specific numbers.
If you're below $190,000 and want to maximize your 401(k) contribution, you may need to run an additional year-end paycheck to increase your W-2 base — do this before December 31.
2026 Roth catch-up mandate (SECURE 2.0 §603)
If your W-2 wages from any employer exceeded $145,000 in 2025, your 2026 catch-up contributions (the $8,000 above the $24,500 base limit) must be designated Roth — you cannot make them pre-tax. This affects dentists age 50+ who pay themselves a W-2 from an S-corp. Confirm your plan documentation and payroll software handle this correctly before year-end.
4. Roth conversion window: act before December 31
Roth conversions must be completed by December 31 of the tax year — there's no extension. A conversion processed January 2, 2027 counts for 2027, not 2026.
Year-end is the one time when you know (approximately) your 2026 taxable income and can calculate exactly how much bracket space remains. The goal is to convert enough to fill your current bracket without spilling into the next one.
| 2026 MFJ taxable income bracket top | Marginal rate on conversion | Typical dentist scenario |
|---|---|---|
| Up to $100,800 | 22% | Associate or part-time dentist — often a good conversion target |
| $100,800 – $211,400 | 24% | Post-sale gap year or semi-retirement — primary Roth window |
| $211,400 – $403,550 | 32% | Peak practice owner — converting is usually suboptimal unless planning for RMD risk |
| $403,550 – $512,450 | 35% | High-earning specialist — only convert if anticipating 37% RMDs |
IRMAA warning: Roth conversions increase your MAGI for the year — and Medicare IRMAA surcharges are calculated on your MAGI from two years prior. A large conversion in 2026 will affect your 2028 Medicare Part B and Part D premiums. The 2026 IRMAA threshold starts at $109,000 single / $218,000 MFJ (based on 2024 income); expect similar thresholds when the IRS publishes 2028 IRMAA. If you're 63–64 now, plan accordingly. See the IRMAA planning guide for the surcharge tiers.
5. HSA contributions: fund by April 15, but invest now
HSA contributions for 2026 can be made up to April 15, 2027 — but if you haven't already invested your HSA balance (many people leave it in cash), December is a good time to address this. The 2026 HSA contribution limits are:4
- Self-only HDHP coverage: $4,400
- Family HDHP coverage: $8,750
- Age 55+ catch-up: $1,000 additional
As a self-employed dentist, you deduct the HDHP premium above the line via the self-employed health insurance deduction (SEHID) — and then also deduct HSA contributions. The two stack, which is rare in the tax code. A dentist paying $24,000/year in family HDHP premiums plus maxing the $8,750 HSA gets $32,750 in above-the-line deductions, reducing QBI and SE income as well as ordinary income.
6. Charitable giving: complete by December 31
Charitable deductions apply to the year the contribution is made. For dentists who want to give, two vehicles are especially useful:
Donor-advised fund (DAF): bunch multiple years in one
A DAF allows you to contribute cash or appreciated securities in a single year (getting the full deduction), then recommend grants to charities over multiple years. In a high-income year — especially a year you're selling a practice or receiving a DSO earnout — front-loading a DAF contribution lets you take a large deduction at the 37% rate and distribute grants at a pace that suits you.
Example: you net $700,000 in 2026 due to a partial DSO earnout. Normally you'd give $20,000/year to your university dental school. Instead, you contribute $100,000 to a DAF in December 2026, deducting it at your 37% rate. You recommend $20,000 grants for the next five years. Net tax benefit vs. annual giving: roughly $14,800 (the 37% vs. 24% rate difference on the accelerated contribution).
Qualified charitable distributions (QCD): if you're 70½ or older
If you're 70½ or older and have a traditional IRA, you can direct up to $111,000 (2026) directly from your IRA to charity — tax-free, and it counts toward your required minimum distribution.5 The QCD doesn't appear in your AGI, which is better than a deduction for dentists who take the standard deduction or whose charitable contributions don't clear the deduction threshold. A QCD must be processed by December 31; IRA custodians need several business days, so initiate in early December.
7. Q4 estimated taxes: due January 15, 2027
Your fourth 2026 estimated tax payment covers income from September 1 – December 31. The due date is January 15, 2027. To avoid an underpayment penalty, your four 2026 payments combined must cover either:
- 100% of your 2025 federal tax liability (if 2025 AGI was ≤$150,000), or
- 110% of your 2025 federal tax liability (if 2025 AGI exceeded $150,000), or
- 90% of your actual 2026 tax liability
Most dental practice owners use the 110% safe harbor because it's predictable — look at line 24 of your 2025 Form 1040, multiply by 110%, subtract what you already paid in Q1–Q3, and pay the balance by January 15.
If you made large retirement contributions in Q4 (cash balance plan, solo 401(k) top-off), your actual 2026 tax bill will be meaningfully lower than the safe harbor calculation suggests. You don't need to overpay based on safe harbor — but make sure the safe harbor payment itself is made on time to avoid the penalty.
See the full estimated taxes guide for the SE tax breakdown and S-corp payroll solution.
8. Review and coordinate with your advisors
Several year-end decisions require information from other advisors before you can finalize them:
| Item | Who you need to talk to | Why before year-end |
|---|---|---|
| Cash balance plan contribution amount | TPA / actuary | Must fund within actuarial range; need number before you can plan cash flow |
| S-corp reasonable comp check | CPA | Year-end payroll adjustment requires live payroll run before Dec 31 |
| Roth conversion amount | CPA (for bracket calculation) + financial advisor (for IRMAA impact) | Must be processed by Dec 31; bracket math requires knowing full-year income |
| Large equipment purchase timing | CPA (for tax impact) + practice consultant (for clinical need) | Placed-in-service deadline is Dec 31 regardless of invoice date |
| DAF contribution sizing | Financial advisor + CPA | Optimal amount depends on bracket, AGI, and whether you itemize |
| Buy-sell / estate plan review | Attorney + financial advisor | Not tax-deadline driven, but year-end is a natural annual review trigger |
Year-end checklist summary
| Action | Deadline | Potential tax impact |
|---|---|---|
| Establish Solo 401(k) if not already done | December 31, 2026 | Enables up to $72,000+ in 2026 deductions |
| Make 401(k) employee deferral election / final paycheck | December 31, 2026 | $24,500–$35,750 deduction depending on age |
| Coordinate cash balance plan contribution | With actuary by October; fund by April 15 | $80K–$290K additional deduction depending on age |
| Place equipment in service | December 31, 2026 | Full first-year deduction at 100% bonus dep rate |
| S-corp reasonable comp / year-end payroll adjustment | December 31, 2026 | Affects 401(k) employer match, FICA, QBI phase-out |
| Roth conversion (if appropriate) | December 31, 2026 | Bracket-dependent; 22–24% rate is favorable for post-sale dentists |
| DAF contribution or direct charitable donations | December 31, 2026 | Deductible at current-year marginal rate |
| QCD from IRA (age 70½+) | December 31, 2026 (initiate early December) | Up to $111,000 excluded from AGI |
| Q4 estimated tax payment | January 15, 2027 | Avoids underpayment penalty on 2026 income |
| HSA contribution top-off | April 15, 2027 | $4,400–$8,750 above-the-line deduction |
| Solo 401(k) employer contribution deposit | April 15 or Oct 15 with extension | Up to $47,500 (S-corp) or $47,500 (sole prop, income-based) |
| IRA or backdoor Roth contribution | April 15, 2027 | $7,500 per spouse |
Talk to an advisor before the deadlines pass
The difference between a dentist who runs this checklist annually with coordinated advisors and one who files in April and hopes for the best is often $50,000–$150,000 in annual tax savings. These aren't exotic strategies — they're standard practice owner planning executed on the right timeline.
A fee-only financial advisor who focuses on dental practice owners knows these deadlines, coordinates with your CPA and TPA, and can run the scenarios before year-end when they still matter.
Sources
- IRS — 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500: 2026 employee deferral limit $24,500; IRA contribution limit $7,500; catch-up provisions per IRC §414(v) and SECURE 2.0 ages 60–63 super catch-up.
- IRS — Publication 946, How to Depreciate Property: Section 179 mechanics, placed-in-service requirement, income limitation, and carryforward rules. 2026 §179 limit $2,560,000 per IRS inflation adjustment.
- IRS — IRS releases tax inflation adjustments for tax year 2026, including amendments from the One Big Beautiful Bill: 100% bonus depreciation restored permanently for property placed in service after January 19, 2025 (OBBBA §10102); 2026 MFJ bracket thresholds; standard deduction $32,200 MFJ.
- IRS — Publication 969, Health Savings Accounts and Other Tax-Favored Health Plans: 2026 HSA contribution limits $4,400 self-only / $8,750 family; age-55+ catch-up $1,000; HDHP minimum deductible and out-of-pocket maximum thresholds.
- IRS — Retirement Plan and IRA Required Minimum Distributions FAQs: Qualified charitable distribution rules under IRC §408(d)(8); 2026 QCD limit $111,000 per IRS Rev. Proc. 2025-67; QCD counts toward RMD; age 70½ eligibility requirement.
All dollar amounts and thresholds reflect 2026 tax year rules. Solo 401(k) deferral limit $24,500 per IRS Rev. Proc. 2025-67 (IRS source 1). Bracket thresholds per IRS 2026 inflation adjustments (IRS source 3). Values verified May 2026.