Disclaimer: This article is for informational purposes only and does not constitute tax advice or create a CPA-client relationship. Retirement plan rules are complex and depend on your specific situation. Consult a licensed CPA before making plan selection decisions. Last updated: July 14, 2026.
In This Article
- What Retirement Plan Choice Do Most NJ Self-Employed People Get Wrong?
- What Are the 2026 Contribution Limits for NJ Self-Employed Retirement Plans?
- How Does a SEP-IRA Work for NJ Self-Employed Individuals?
- Why Is the Solo 401(k) the Most Flexible Retirement Plan for NJ Owner-Only Businesses?
- When Should a NJ Small Business Use a SIMPLE IRA Instead of a 401(k)?
- How Can High-Income NJ Practitioners Use Defined Benefit Plans to Save More?
- Why Does NJ's Non-Conformity on Retirement Deductions Matter So Much?
- What Does the SEP-IRA vs. Solo 401(k) Tax Difference Look Like in Real Numbers?
- Your Retirement Plan Decision Checklist
- Sources and References
- Frequently Asked Questions
- Ready to File With Confidence?
What NJ Self-Employed People Need to Know About Retirement Plans
When a self-employed person or S-corp owner asks what retirement plan to set up, the most common answer they get is: "Just open a SEP-IRA. It's simple."
That advice is often correct from a federal-tax standpoint - but it ignores a real NJ-specific advantage for the Solo 401(k). Per N.J.S.A. 54A:6-21, employee 401(k) elective deferrals ARE excludable from NJ gross income; NJ guidance describes the exclusion for 401(k) contributions generally and does not clearly address employer match/profit-sharing contributions to a Solo 401(k), so confirm that share for your facts. By contrast, N.J.S.A. 54A:6-26 disallows NJ deductions for traditional IRA contributions, and SEP-IRA / SIMPLE IRA contributions are NOT excludable from NJ gross income (they create NJ basis instead). So for NJ residents, the Solo 401(k) delivers both federal AND contemporaneous NJ tax savings, while SEP-IRA and SIMPLE IRA produce only federal savings (with NJ basis recoverable tax-free later). (Updated May 2026.)
The practical takeaway: choose your plan based on real factors - federal contribution limits, employee coverage rules, plan administration costs, Roth options, loan provisions - AND the NJ deductibility difference. For NJ-resident sole proprietors and S-corp owners, Solo 401(k) is usually the most NJ-tax-efficient choice; SEP-IRA contributes only federal savings + deferred NJ basis recovery.
This guide covers all four main retirement plan options for self-employed NJ taxpayers, the 2026 limits, and the NJ state-tax mechanics most CPAs don't discuss correctly.
What Are the 2026 Contribution Limits for NJ Self-Employed Retirement Plans?
| Feature | SEP-IRA | Solo 401(k) | SIMPLE IRA | Defined Benefit (Cash Balance) |
|---|---|---|---|---|
| 2026 employee limit | N/A | $24,500 | $17,000 | N/A |
| 2026 employer/total limit | $72,000 | $72,000 | 3% match | Up to $290,000 §415(b) annual benefit |
| Catch-up (50+) | N/A | $8,000 | $4,000 | Actuarially determined |
| Enhanced catch-up (60–63) | N/A | $11,250 | $5,250 | N/A |
| Roth option | No | Yes | Yes (SECURE 2.0) | No |
| Loan provision | No | Yes (up to $50K) | No | Varies |
| Employees allowed | Yes | No (owner + spouse only) | Yes (must offer all) | Varies |
| Admin complexity | Very low | Low–medium | Low | High (actuary required) |
| Establishment deadline | Tax filing deadline | Employer contributions: filing deadline incl. extensions (SECURE sec. 201); employee deferral election: Dec 31 | October 1 | Filing deadline incl. extensions (SECURE sec. 201) |
| NJ deductibility | No (creates NJ basis) | Deferrals: Yes per N.J.S.A. 54A:6-21; employer share not clearly addressed - confirm for your facts | No (creates NJ basis) | No (creates NJ basis; 54A:6-21 covers only 401(k) plans) |
How Does a SEP-IRA Work for NJ Self-Employed Individuals?
A SEP-IRA (Simplified Employee Pension) is the simplest retirement plan for self-employed individuals. There are no annual filings, no contribution formulas to track, and minimal administrative burden.
How contributions work: You contribute as the employer. For a sole proprietor or working partner, a 25%-of-compensation plan rate works out to roughly 20% of adjusted net self-employment earnings after the deductible portion of self-employment tax and the contribution-rate adjustment, up to $72,000 for 2026. Do not multiply Schedule C profit by 25%; use the IRS Publication 560 worksheet. For a W-2 employee of your own S-corp, the limit is 25% of W-2 wages, up to $72,000.
The catch: SEP-IRA contributions are made on the employer side only. There's no employee deferral component. If you have employees, you must contribute the same percentage for all eligible employees. This is why many sole proprietors outgrow the SEP-IRA once they hire.
Federal tax benefit: The SEP-IRA contribution is deductible on Schedule 1 (Form 1040), reducing your federal AGI.
NJ tax benefit: None. New Jersey does not allow deductions for SEP-IRA contributions on the NJ-1040. Your NJ taxable income is unchanged by the SEP-IRA contribution. As a result, you will have a higher NJ basis in the account. Withdrawals in retirement that represent after-NJ-tax contributions are partially excluded from NJ income.
Why Is the Solo 401(k) the Most Flexible Retirement Plan for NJ Owner-Only Businesses?
The Solo 401(k) (also called individual 401(k) or self-employed 401(k)) is designed specifically for self-employed individuals and owners of businesses with no full-time employees other than the owner and spouse.
Two-part contribution structure:
- Employee deferral: Up to $24,500 for 2026 ($32,500 if age 50+, $35,750 if age 60-63 under SECURE 2.0 enhanced catch-up). This reduces your W-2 wages on Box 1 if you are an S-corp employee.
- Employer profit-sharing: Up to 25% of your W-2 compensation (S-corp) or net SE income (sole prop), subject to the combined $72,000 annual limit.
Roth option: SECURE 2.0 Act expanded Roth availability for Solo 401(k)s. If your plan document allows it, you can make Roth employee deferrals, contributions from after-tax income that grow and are withdrawn tax-free.
Loan provision: Solo 401(k)s can allow loans of up to $50,000 or 50% of the vested balance, whichever is less. No SEP-IRA equivalent.
NJ deductibility: the advantage: Per N.J.S.A. 54A:6-21, employee elective deferrals (W-2 Box 12 Code D - allowed since 1984) are excludable from NJ gross income; NJ guidance describes the exclusion for 401(k) contributions generally and does not clearly address Solo 401(k) employer profit-sharing/match contributions - confirm that share for your facts. NJ Box 16 (state wages) is reduced from Box 1 by the amount of pre-tax 401(k) deferrals. This is true contemporaneous NJ tax savings, unlike SEP-IRA / SIMPLE IRA which only create NJ basis. (Updated May 2026.)
Establishment deadline: Under SECURE Act sec. 201, a Solo 401(k) can be adopted as late as your tax-filing deadline (including extensions) and treated as established on the last day of the prior year, so employer profit-sharing contributions can still be made for that year. December 31 remains the deadline for employee deferral elections (a sole proprietor's first plan year gets until the unextended filing deadline under SECURE 2.0 sec. 317).
When Should a NJ Small Business Use a SIMPLE IRA Instead of a 401(k)?
The SIMPLE IRA (Savings Incentive Match Plan for Employees) is designed for small businesses with up to 100 employees who want to offer employees a retirement benefit without the complexity of a full 401(k) plan.
Employee deferrals: Up to $17,000 for 2026 per IRS Notice 2025-67 (up from $16,500 in 2025); $21,000 if age 50+; $22,250 if age 60–63 under SECURE 2.0 enhanced catch-up.
Employer obligation: You must either match employee deferrals up to 3% of compensation, OR make a flat 2% non-elective contribution for all eligible employees (even non-participants). The 2% option applies to all employees. You can't opt out.
Roth option: SECURE 2.0 added a Roth option for SIMPLE IRAs, effective 2023.
Key limitation: If you withdraw from a SIMPLE IRA within 2 years of the first contribution, the early withdrawal penalty is 25% (not the usual 10%). This "2-year lock" makes SIMPLEs less flexible than 401(k)s for participants who may need early access.
NJ deductibility: Unlike 401(k) employee deferrals (which ARE excludable from NJ gross income per N.J.S.A. 54A:6-21), SIMPLE IRA employee deferrals are NOT excludable for NJ purposes. NJ Box 16 includes the deferred amount even though federal Box 1 is reduced. The deferrals create NJ basis recoverable tax-free in retirement under the 3-Year Rule or General Rule. Employer match/non-elective contributions to a SIMPLE IRA also create NJ basis rather than producing a current-year NJ deduction.
How Can High-Income NJ Practitioners Use Defined Benefit Plans to Save More?
A cash balance plan or traditional defined benefit plan allows contributions far beyond the $72,000 defined contribution limit. The 2026 §415(b) annual benefit limit is $290,000 per IRS Notice 2025-67 (up from $280,000 in 2025); annual contributions often fall in the $100,000–$290,000 range depending on age and target benefit for owners in their late 40s or 50s. This makes them ideal for physicians, attorneys, CPAs, and other high-income practitioners who want to aggressively build retirement savings and reduce taxable income.
The defined benefit promise specifies a projected benefit at retirement. An actuary certifies the annual funding requirement. Contributions to fund the promised benefit are deductible.
NJ deductibility: Employer contributions to a qualified defined benefit plan are generally deductible for NJ purposes.
The catch: Annual actuarial cost (~$1,500–$3,000/year) and minimum funding requirements. Once established, you are obligated to fund the plan at actuarially required levels.
Why Does NJ's Non-Conformity on Retirement Deductions Matter So Much?
This is the most important section for NJ taxpayers, and the one most CPAs don't discuss.
New Jersey conforms to federal rules on what contributions can be made, but not to federal rules on deductibility. Specifically:
- NJ-1040 does not allow deductions for IRA contributions (neither traditional IRA nor SEP-IRA) under N.J.S.A. 54A:6-26. This is explicitly stated in the NJ-1040 instructions at line 27a.
- NJ-1040 does allow deductions for employer contributions to qualified pension, profit-sharing, and 401(k) plans under N.J.S.A. 54A:6-25.
What this means in practice:
| Plan Type | Federal Tax Benefit | NJ Tax Benefit |
|---|---|---|
| SEP-IRA | Deductible (reduces AGI) | Not deductible on NJ-1040 |
| Traditional IRA | Deductible (income limits apply) | Not deductible on NJ-1040 (N.J.S.A. 54A:6-26) |
| Solo 401(k) employer contribution | Deductible (reduces business income) | Not clearly addressed by NJ guidance - confirm for your facts |
| Solo 401(k) employee deferral | Reduces W-2 Box 1 | Excludable from NJ gross income (W-2 Box 16 reduced; N.J.S.A. 54A:6-21) |
| SEP-IRA contribution | Deductible | NOT deductible on NJ return (creates NJ basis recoverable in retirement) |
| SIMPLE IRA employee deferral and employer match | Deductible | NOT deductible on NJ return (creates NJ basis) |
| Defined benefit plan employer contribution | Deductible | Taxable for NJ - no exclusion (54A:6-21 covers only 401(k) plans); creates NJ basis |
The accurate consequence: Per N.J.S.A. 54A:6-21, NJ allows a current-year exclusion for 401(k) employee elective deferrals - NJ gross income / NJ Box 16 wages are reduced just like federal Box 1. NJ guidance does not clearly address Solo 401(k) employer contributions - confirm that share for your facts. Defined benefit employer contributions are taxable for NJ (the 54A:6-21 exclusion covers only 401(k) plans). However, SEP-IRA, SIMPLE IRA, and Traditional IRA contributions are NOT excludable from NJ gross income - they create NJ basis in the retirement account recoverable tax-free in retirement under the 3-Year Rule (full recovery in first 36 months of distributions) or General Rule (proportional). For NJ-resident business owners, Solo 401(k) is the most NJ-tax-efficient retirement plan choice.
If you fund a Solo 401(k) with $72,000, your federal AGI drops by $72,000; for NJ, the employee-deferral share clearly reduces NJ gross income, and the employer share should be confirmed for your facts. If you fund a SEP-IRA with $72,000, federal AGI drops by $72,000 but NJ gross income does not change in the contribution year (you instead get NJ basis recoverable later). This NJ-treatment difference per N.J.S.A. 54A:6-21 - clear at least for the deferral share - is one of the strongest reasons NJ-resident business owners prefer Solo 401(k) over SEP-IRA when feasible. (Updated May 2026.)
What Does the SEP-IRA vs. Solo 401(k) Tax Difference Look Like in Real Numbers?
Scenario: NJ S-corp owner (single filer), $200,000 W-2 from S-corp, NJ taxable income of $200,000 before retirement contribution. At $200K single, NJ marginal rate is 6.37% (the 6.37% bracket runs $75,001-$500,000 single; 8.97% kicks in at $500K, 10.75% kicks in at $1M).
| SEP-IRA ($50,000) | Solo 401(k) Employer ($50,000) | |
|---|---|---|
| Federal AGI reduction | $50,000 | $50,000 |
| Federal tax saved (at 24% bracket) | $12,000 | $12,000 |
| NJ income reduction (current year) | $0 | $50,000 |
| NJ tax saved (current year) | $0 | ~$3,185 |
| NJ basis created (recoverable tax-free in retirement) | $50,000 | $0 |
| Total current-year tax saved | $12,000 | ~$15,185 |
Choice between Solo 401(k) and SEP-IRA depends on federal contribution limits, employee coverage, Roth options, loan provisions, admin costs, AND a real NJ deduction differential: per N.J.S.A. 54A:6-21 the Solo 401(k) employee deferral reduces NJ gross income (about $1,561 of NJ tax at 6.37% on a $24,500 deferral) while the SEP-IRA only creates NJ basis recoverable later; the Solo 401(k) employer share is not clearly addressed by NJ guidance - confirm it for your facts. Neither owner contribution is a Schedule C expense or reduces self-employment tax.
Your Retirement Plan Decision Checklist
- [ ] Do you have any full-time employees other than yourself and your spouse? (If yes, Solo 401(k) is not available)
- [ ] What is your net self-employment or W-2 income from your business?
- [ ] Have you established a plan before? If not, remember a Solo 401(k) can be adopted up to your filing deadline (incl. extensions) for prior-year employer contributions, while employee deferral elections generally must be set by December 31.
- [ ] Do you want a Roth option for tax-free growth?
- [ ] Do you want a loan provision for emergency access?
- [ ] What is your NJ tax rate on the last dollar of income?
- [ ] Have you modeled the federal vs. NJ tax savings for each plan type?
Sources and References
- IRC §402 (Solo 401(k) deductibility)
- IRC §408 (IRA rules)
- IRC §219 (IRA deduction, federal)
- N.J.S.A. 54A:6-25 (NJ deduction for qualified plan contributions)
- N.J.S.A. 54A:6-26 (NJ non-conformity with IRA deductions)
- NJ-1040 Instructions, Line 27a (IRA deduction. NJ)
- IRS Publication 560 (Retirement Plans for Small Business)
- SECURE 2.0 Act of 2022 (Pub. L. 117-328)
For a personalized analysis of retirement plan options for your NJ business, contact Monaco CPA at /services/retirement-planning.
Frequently Asked Questions
Can I contribute to both a Solo 401(k) and a SEP-IRA in the same year?
An employer may maintain a SEP and another qualified plan for the same business, but plan documents, elective-deferral coordination, and the combined IRC §415(c) limits must be applied. The simplified Form 5305-SEP generally cannot be used when the employer maintains another qualified plan unless that other plan is also a SEP; a prototype or individually designed SEP may be needed. Coordinate the plan documents and contribution limits before funding both.
What's the deadline to establish a Solo 401(k)?
Under SECURE Act sec. 201, a Solo 401(k) can be adopted as late as your tax-filing deadline (including extensions) for the prior year and treated as established on December 31 - so you can open a plan in 2027 and make 2026 employer profit-sharing contributions. December 31 still matters for employee deferrals: elections must generally be in place by year-end (S-corp owners defer through payroll during the year), except that under SECURE 2.0 sec. 317 a sole proprietor may make first-plan-year employee deferrals up to the unextended filing deadline.
Why does NJ not allow IRA deductions?
New Jersey's income tax was designed with its own set of deductions that don't mirror federal law. Under N.J.S.A. 54A:6-26, NJ specifically excludes IRA deductions. The silver lining: because you don't get a NJ deduction when you contribute, your after-NJ-tax basis in the IRA is higher. When you withdraw in retirement, the basis is excluded from NJ income tax under the NJ IRA exclusion rules.
I have a SEP-IRA already set up. Should I switch to a Solo 401(k)?
Possibly. You can open a Solo 401(k) for the current tax year and stop making SEP-IRA contributions (or terminate it if you prefer simplicity). Existing SEP-IRA funds can remain in the SEP-IRA or roll over to the Solo 401(k) if the plan allows it. The analysis of whether to switch depends on your current contribution level, NJ tax rate, and administrative preferences. I'd recommend running the numbers with a CPA before switching.
Related reading: NJ Tax Calendar | Services | About Greg Monaco | Contact
Ready to File With Confidence?
Tax rules change frequently. If anything in this guide applies to your situation, a quick review with a CPA can prevent costly mistakes. Greg Monaco is a NJ-licensed CPA (License #20CC04711400). Greg remains responsible for every engagement and reviews, approves, and signs all client-facing work. Trained staff may assist under his direct supervision and confidentiality procedures.