Yes, if the business pays your spouse. They can join your Solo 401(k) as a second participant, and each of you gets your own limits: up to $24,500 of employee deferrals in 2026, plus an employer contribution, with an overall cap of $72,000 per person. Your spouse needs real compensation from the business to contribute. Being married to the owner is not enough. The plan also keeps the simple “one-participant” status, as long as your spouse is the only other person in it.
How much can each spouse contribute?
Each spouse is treated as a separate participant, with a separate compensation base:
- Employee deferrals: up to $24,500 each in 2026, or $32,500 from age 50 (the IRS puts the catch-up at $8,000, and at $11,250 for ages 60 to 63).
- Employer contribution: up to 25% of a W-2 spouse’s wages. A co-owner uses the IRS’s special self-employed calculation instead, which our calculator runs.
- Overall cap: the lesser of $72,000 or 100% of that person’s compensation, before catch-up.
Between the two of you, the ceiling is $144,000 before catch-ups (2 x $72,000, our arithmetic). You only get near it with high earnings: at $250,000 of profit, the calculator gives $71,543 for one person. Most small households land far lower, as the examples below show.
Your spouse needs their own earned income
A 401(k) contribution, whether an elective deferral or an employer (profit-sharing) contribution, is based on compensation. No compensation, nothing to contribute. There are two common ways to give your spouse some:
- Your spouse is a W-2 employee of the business. Their wage is their compensation for plan purposes.
- You run the business as a qualified joint venture. If you and your spouse materially participate as the only members of the business and file a joint return, you can elect to split it into two Schedule Cs. Each of you then has your own net self-employment earnings, per the Schedule SE instructions.
The IRS defines a one-participant 401(k) as “a traditional 401(k) plan covering a business owner with no employees, or that person and his or her spouse,” on its page for one-participant 401(k) plans. A spouse who works in the business keeps you inside that definition. If you are still comparing plans, the Solo 401(k) vs. SEP IRA comparison shows what each allows.
Example 1: spouse as co-owner (qualified joint venture)
Say the business earns $90,000 of net profit and you split it 50/50 as a qualified joint venture, both under 50. Each of you reports a $45,000 share on a separate Schedule C and runs it through the Solo 401(k) contribution calculator:
| Deferral | Employer | Total | |
|---|---|---|---|
| You | $24,500 | $8,364 | $32,864 |
| Your spouse | $24,500 | $8,364 | $32,864 |
| **Household** | $49,000 | $16,728 | **$65,728** |
You
- Deferral
- $24,500
- Employer
- $8,364
- Total
- $32,864
Your spouse
- Deferral
- $24,500
- Employer
- $8,364
- Total
- $32,864
**Household**
- Deferral
- $49,000
- Employer
- $16,728
- Total
- **$65,728**
Hypothetical profit. Output of the same functions as our Solo 401(k) calculator. The employer share is rounded to the dollar.
If all $90,000 stayed on one Schedule C, you alone could contribute $41,228. Splitting the business opens a second $24,500 deferral limit and a second employer contribution, which is $24,500 more for the household.
Example 2: spouse as a W-2 employee
Suppose your sole proprietorship would show $90,000 of revenue minus expenses if you paid your spouse nothing, and you pay them a $30,000 wage. Per the Instructions for Schedule C, that creates three deductions on your Schedule C:
- The $30,000 wage (line 26).
- Your employer share of Social Security and Medicare tax on it: 7.65%, or $2,295 (line 23).
- The employer contribution you make for them: $7,500, which assumes the 25% maximum of the wage (line 19). Your own contribution as the self-employed owner goes on Schedule 1 instead.
That leaves $90,000 - $30,000 - $2,295 - $7,500 = $50,205 of Schedule C net profit. In the calculator, $50,205 allows you $33,832: the $24,500 deferral plus a $9,332 employer contribution.
Your spouse’s side starts from their wage: the $7,500 employer contribution plus whatever they elect to defer from it. Total additions for one person cannot pass 100% of their compensation, so on $30,000 they can defer up to $22,500 on top of the $7,500, for $30,000.
| Contribution | |
|---|---|
| You (owner, $50,205 of net profit) | $33,832 |
| Your spouse ($30,000 W-2 wage) | $30,000 |
| Household total | $63,832 |
Paying the wage lowers your own contribution base, through the wage, the matching payroll tax and the plan contribution, but it opens a second deferral limit.
The 100% rule is what keeps a small wage from supporting a large contribution:
| Spouse's wage | Employer (25% max) | Most they can defer | Total |
|---|---|---|---|
| $20,000 | $5,000 | $15,000 | $20,000 |
| $30,000 | $7,500 | $22,500 | $30,000 |
| $40,000 | $10,000 | $24,500 | $34,500 |
| $100,000 | $25,000 | $24,500 | $49,500 |
$20,000
- Employer (25% max)
- $5,000
- Most they can defer
- $15,000
- Total
- $20,000
$30,000
- Employer (25% max)
- $7,500
- Most they can defer
- $22,500
- Total
- $30,000
$40,000
- Employer (25% max)
- $10,000
- Most they can defer
- $24,500
- Total
- $34,500
$100,000
- Employer (25% max)
- $25,000
- Most they can defer
- $24,500
- Total
- $49,500
Hypothetical wages. Employer contribution is 25% of wages (IRS one-participant 401(k) page). The deferral is the smaller of $24,500 or the wage minus the employer contribution, so the total never passes 100% of the wage (Notice 2025-67, Publication 560). Catch-up amounts for age 50 and over are extra. Our arithmetic.
Above roughly $32,700 of wages, the $24,500 deferral limit becomes the constraint instead of the wage. The calculator is built for self-employment profit, so it does not cover this W-2 side of the plan. Work it out directly as above.
When this does not apply, or gets smaller
- Your spouse has no pay from the business. Informal, unpaid help gives them no compensation to contribute against, however much they do.
- Your spouse also defers at a day job. The deferral limit follows the person: the IRS says an owner who is also employed by a second company has limits on elective deferrals “by person, not by plan.” Take the $45,000 joint-venture share from Example 1 with $10,000 already deferred at the day job. Your spouse can defer $14,500 into your plan and still gets the $8,364 employer contribution, for $22,864. Your $32,864 stays the same, so the household total is $55,728 instead of $65,728. See also Can I Have a Solo 401(k) and a 401(k) at Work?
- You have other employees. The one-participant setup covers an owner with no employees, or that owner and their spouse. The IRS says the no-testing advantage disappears if you hire employees, and eligible employees must be included in the plan.
- Your business is an LLC or partnership with your spouse as a member. The joint venture election requires a business co-owned by both spouses and not held in the name of a state law entity such as a partnership or an LLC, per Publication 15. Check with a tax professional before counting on two Schedule Cs.
- The plan has an age or service rule. The IRS says a plan generally has to let an employee in once they reach age 21 and have one year of service. A plan can be more generous than that. A spouse under 21 or in their first year may be excluded only if your plan document says so, so read yours.
- Your plan document does not allow a second participant. Ask your provider, and check whether the plan needs its own EIN.
Pick the structure before you pick the plan
If you and your spouse jointly own and operate a business and share profits and losses, Publication 15 says you may be partners whether or not you have a formal agreement. The qualified joint venture is the way out: both spouses must elect it, every item of income, deduction and credit is divided by each spouse’s interest, and each of you files a separate Schedule C and a separate Schedule SE. If your spouse is an employee of your sole proprietorship, none of this applies and the plan math is the W-2 version.
Payroll taxes depend on who the employer is
For a sole proprietorship, Publication 15 says the wages of an individual who works for their spouse in a trade or business are subject to income tax withholding and Social Security and Medicare taxes but not FUTA. That flips for other structures. Wages for a spouse’s services are subject to FUTA as well if the spouse works for a corporation, even one the other spouse controls, or for a partnership in which the spouse is a partner. In those cases the spouse is treated as working for the entity. If you later elect S corporation status, the payroll picture changes, and our S corp election guide covers that choice.
What changes at tax time
On Schedule C, the IRS says line 26 holds salaries and wages but not amounts paid to yourself, line 23 includes Social Security and Medicare taxes you pay to match required withholding from employees’ wages, and line 19 is for contributions made for the benefit of your employees. If the plan includes you as a self-employed person, your own contributions go on Schedule 1, line 16, instead of Schedule C. That is why your spouse’s employer contribution reduces your Schedule C profit and your own does not.
The plan also has a reporting duty. The IRS says a one-participant 401(k) is generally required to file Form 5500-EZ if it has $250,000 or more in assets at the end of the year, and a plan with fewer assets may be exempt. Our reading is that the threshold applies to the plan’s total assets, so add up both accounts.
Before you add your spouse
- Decide whether your spouse will be a W-2 employee or a co-owner in a qualified joint venture, and check that your entity type allows the second option.
- Set the wage first, since it caps what the plan can accept for your spouse.
- Confirm that your plan document lets a second person participate.
- If you also use a SEP IRA, read how a SEP IRA and a 401(k) work together, because the contributions share one limit.
- Re-run your own contribution on the profit that is left after the wage, the employer taxes and the plan contribution.
- If your spouse also has a 401(k) at another job, subtract that deferral from their $24,500.
How we got these figures
The one-participant definition, the 25% employer rate, the testing rule and the $250,000 Form 5500-EZ threshold come from the IRS page on one-participant 401(k) plans. The qualified joint venture rules come from the Schedule SE instructions and Publication 15 (2026), which also supplies the spouse wage and FUTA rules. The Schedule C lines come from the Instructions for Schedule C. The $24,500 limit, the catch-up amounts and the $72,000 limit come from IR-2025-111 and Notice 2025-67, the 100% of compensation rule from Publication 560, and the age 21 and one-year rule from the IRS page on 401(k) plan qualification requirements. We opened them between October 14 and 21, 2026 and quote the passages in our research file. The household examples come from the same functions as our Solo 401(k) calculator, and the wage table and the $144,000 ceiling are our own arithmetic. All figures are federal and hypothetical.
This is general information, not tax or legal advice. Plan documents and entity types change the answer, so confirm the structure with your plan provider and a tax professional before you add a participant.
