Best 401(k) Providers for Small Business 2026

§1What small business 401(k) actually costs

Most 401(k) providers charge a base monthly fee plus a per-participant monthly fee, and a couple charge a single flat fee instead. At 10 participants, the difference between providers can be $100 or more per month. At 50 participants, the gap can reach $500 per month.

Representative pricing for a 15-person team: Guideline's Starter plan is $49/month base + $6/participant = $139/month, but Starter does not support employer contributions; the Core plan that does is $119/month + $8/participant = $239/month. Human Interest's Complete plan at $180/month + $7/employee = $285/month. ShareBuilder starts at $95/month for a company plan with employees (its advertised $25/month tier is the solo-401(k) product for owner-only businesses, not a small-team price, a distinction that is easy to miss on the pricing page). Ubiquity's flat-fee tiers run $19 to $257/month depending on service level and headcount, with no per-participant add-on; the $19 figure, like ShareBuilder's $25, is a solo-owner tier rather than a small-team price.

§2Guideline: best for Gusto and Rippling users

Guideline integrates natively with Gusto and Rippling. Employee contribution elections flow automatically, employer matches calculate against each payroll run, and W-2 Box 12 reporting is handled without manual entry. This payroll sync is the main reason Guideline dominates the Gusto market; see our Gusto Benefits review for how the health insurance side of the same account works.

Fund menu uses low-cost Vanguard and Fidelity index funds averaging 0.06% expense ratio. Annual nondiscrimination testing, Form 5500 preparation, and ERISA compliance are included. Guideline does not offer self-directed brokerage windows, the fund menu is curated index funds only, which works well for most employees but may not satisfy finance-savvy staff who want individual securities.

On G2, Guideline sits at 4.5 out of 5 across more than 1,150 verified reviews (G2, checked 2026-08-26). The recurring theme in the reviews is that setup and the payroll sync are painless, while the complaints cluster around support response times during open enrollment season, when every plan sponsor is asking questions at once.

§3Human Interest: the better pick off Gusto

Human Interest does not require a specific payroll provider the way Guideline leans on Gusto. It connects to a broader list of payroll systems and offers a fund menu that goes beyond the Vanguard/Fidelity index lineup, which matters if your team has asked for target-date funds from other families or a slightly different risk mix.

The tradeoff is price. The Essentials plan starts at $80/month plus $5 per eligible employee, and the Complete plan (the one most 15-to-40-person teams end up on) runs $180/month plus $7 per employee. That is roughly $285/month for a 15-person team on Complete, well above Guideline's comparable tier. Human Interest's $499 setup fee shows up on the pricing page but gets waived often enough that it is worth asking about before you budget for it. If your broker already manages benefits enrollment through a platform like the one covered in our Employee Navigator review, ask whether that broker relationship extends to 401(k) administration before adding a separate provider.

Human Interest holds 4.3 out of 5 on G2 across more than 2,300 reviews (G2, checked 2026-08-26), a larger review base than Guideline's but a slightly lower average, with reviewers most often flagging the price jump as participant count grows.

§4ShareBuilder and Ubiquity: the flat-fee options for very small teams

ShareBuilder 401(k) and Ubiquity Retirement + Savings both skip the "base fee plus per-participant fee" model that Guideline and Human Interest use, and that structure matters most for teams under 10 people, where a per-participant fee barely moves the total but a flat fee can.

ShareBuilder starts at $95/month for a company plan with employees (its $25/month tier is the solo-401(k) product for owner-only businesses with no staff, not a small-team option, a distinction the pricing page does not make obvious at first glance). Under a Safe Harbor structure with 11 to 25 participants, the monthly administration fee runs $145 if plan assets stay under $500,000 and drops to $100 once assets pass that mark, so the price actually falls as the plan matures.

Ubiquity's flat-fee range runs $19 to $257/month. The $19 figure is its solo-owner plan (billed annually, plus a one-time $285 setup fee), the same kind of owner-only pricing ShareBuilder advertises at $25; a small business with actual employees on payroll lands higher up that range. What stays constant across tiers is the flat structure: a 15-person team on Ubiquity pays the same amount whether the plan holds $50,000 or $2 million, while a percentage-based provider's asset fee grows with the balance. The tradeoff is that Ubiquity's admin support is priced by service tier rather than bundled the way Guideline's is, so it pays to compare the exact tier against what Guideline or Human Interest include by default.

§5Safe Harbor plans: the simplest way to avoid discrimination testing

Standard 401(k) plans require annual nondiscrimination testing to ensure highly compensated employees (earning over $160,000 in 2026, per IRS Notice 2025-67) are not contributing disproportionately. If the test fails, the IRS requires refunding excess contributions, a tax headache for founders.

A Safe Harbor 401(k) avoids this by requiring employer contributions for all eligible employees. The most common structure: a 3 percent non-elective contribution for all eligible employees, or a 100 percent match on the first 3 percent plus a 50 percent match on the next 2 percent of compensation. All major small-business 401(k) providers support Safe Harbor designs, and for companies with even a few high earners, the employer contribution cost often beats the annual refund headache.

See also: best benefits software for small business for related options.

§6SECURE 2.0's auto-enrollment mandate: who actually has to comply

Any 401(k) or 403(b) plan established after December 29, 2022 has to automatically enroll eligible employees once the plan year beginning in 2025 arrives, starting them at a default deferral rate of 3 to 10 percent of pay. That rate then climbs by 1 percentage point every plan year until it reaches at least 10 percent, with a 15 percent ceiling. Employees keep the right to opt out or set their own rate; the mandate just changes the default from "not contributing" to "contributing unless you say otherwise."

Three groups are exempt: plans that existed before December 29, 2022 are grandfathered in, businesses that normally employ 10 or fewer people are exempt outright, and any employer that has been in business for less than three years does not have to comply yet. A team of 8 people setting up its first 401(k) this year does not need auto-enrollment; the same team crossing 10 employees would need to add it. Providers have until December 31, 2026 to formally amend plan documents for the change, even though plans were expected to operate this way starting January 1, 2025 for calendar-year plans.

When you are comparing providers for a new plan, ask directly whether auto-enrollment is included in setup and which fund they use as the default (the "qualified default investment alternative," usually a target-date fund). It is a standard feature across Guideline, Human Interest, ShareBuilder, and Ubiquity, but the default fund choice differs and is worth confirming rather than assuming. If you are switching providers mid-year rather than starting fresh, ask the new provider to reconcile existing employee deferral elections against the mandated default before the first payroll run on the new platform, so nobody is accidentally reset to the auto-enroll rate after already opting in at a different percentage.

§7Frequently asked questions

How much does Guideline actually cost per month? Guideline's Starter plan runs $49/month base plus $6 per active participant, but Starter does not support employer contributions. The Core plan, which does, is $119/month base plus $8 per participant. For a 15-person team, that is $139/month on Starter or $239/month on Core, before the 0.15-0.35 percent annual account fee charged to participant balances (Gusto Retirement Help Center, checked 2026-08-26).

What happens to 401(k) fees when an employee leaves? Most providers, including Guideline, charge a separate monthly base fee for former employees who still have a balance in the plan. Guideline's is $4/month per former employee, starting after a 90-day grace period, so cleaning up old accounts (via rollover) keeps costs down.

Is Human Interest more expensive than Guideline? Generally yes for small teams that need employer contributions. Human Interest's Complete plan is about $180/month plus $7/employee/month, above Guideline's $239/month Core-tier estimate for a 15-person team, though Human Interest offers a wider non-Vanguard/Fidelity fund menu and works with more non-Gusto payroll systems.

Do all small business 401(k) providers charge setup fees? Not always, and even when listed, they are often negotiable or waived. Human Interest lists a $499 installation fee but frequently waives it as part of ongoing promotions, so it is worth asking directly before assuming it applies to you.

What is a Safe Harbor 401(k) and do I need one? A Safe Harbor plan requires employer contributions for all eligible employees (commonly a 3 percent non-elective contribution or a matching formula) in exchange for skipping the annual nondiscrimination test. If you have even a few employees earning above the IRS highly-compensated threshold, Safe Harbor usually costs less than the risk of a failed test and refunded contributions.

Does my company have to auto-enroll employees under SECURE 2.0? Only if the plan was established after December 29, 2022, your business normally has more than 10 employees, and the company has been operating for at least three years. Smaller or newer businesses are exempt from the mandate, though nothing stops them from adding auto-enrollment voluntarily (IRS guidance on mandatory automatic enrollment, checked 2026-08-26).

What are the 401(k) contribution limits for 2026? Employees can defer up to $24,500 of salary into a 401(k) in 2026. Workers 50 and older get an extra $8,000 catch-up contribution, and under SECURE 2.0's newer tier, those aged 60 to 63 get a larger $11,250 catch-up instead (IRS, 401(k) limit increases to $24,500 for 2026).