What is a pooled employer plan?
What a PEP is under ERISA §413(e), what a pooled plan provider must do, and how a PEP differs from a single-employer 401(k) — including what stays with the employer.
401(k) guides for small businesses
Plain-language explanations of how a small business 401(k) actually works — what a pooled employer plan is, what a 3(16) administrator takes on, and what it takes to start a plan. Every figure is cited to its primary source at dol.gov or irs.gov.
These guides answer the questions employers ask before they choose anything: what the roles mean, what actually transfers to a provider, what stays with the business, and which federal rules apply. They are written to be read once and used as a reference, not to sell.
All guides
How to start a 401(k) for a small business
The four steps the IRS sets out, who does what, the federal startup credits and their conditions, and the duties that do not move whichever route you take.
Fiduciary offload and 3(16) administration
What a 3(16) plan administrator actually takes on, what a 3(38) investment manager is for, and the fiduciary duties an employer keeps regardless.
401(k) eligibility rules: who you have to cover
The strictest conditions a plan may impose, why a two-year waiting period cannot apply to deferrals, and the long-term part-time rule that reached more employers from 2025.
Connecting payroll to a 401(k)
What actually moves between payroll and a 401(k) each pay period, why deferral deposit timing is a fiduciary matter, and what breaks when the transfer is done by hand.
401(k) plan documents: what each one is for
The documents a 401(k) runs on — plan document, summary plan description, summary annual report — who has to receive each, and what happens when the plan changes.
What drives the cost of setting up a 401(k)
Why there is no single price: the service roles you buy separately, how payroll data reaches the plan, the audit threshold that changed in 2023, and the federal credits and their conditions.
How long it takes to set up a 401(k)
The rules that actually set the timeline — when a plan can take effect, why deferrals cannot be backdated, and the notice window that fixes your last date to decide.
401(k) compliance testing, explained
What ADP, ACP and top-heavy testing check, when each applies, and the designs that remove them.
401(k) or SIMPLE IRA for a small business?
The contribution limits side by side for 2026, the employer contribution a SIMPLE IRA requires every year, and why the real comparison is usually safe harbor 401(k) versus SIMPLE IRA.
401(k) auto-enrollment rules for small employers
Which new plans must automatically enrol employees, the default and escalation percentages, and the two exemptions that cover most very small employers.
What is a safe harbor 401(k)?
What a safe harbor 401(k) commits an employer to, the contribution formulas that qualify, the notice window, and what it buys.
The 401(k) startup tax credit, and its conditions
The §45E startup credit and the automatic enrolment credit: the amounts, the cap formula, and the three conditions that disqualify more employers than expected.
aipep401k.com is a pooled employer plan for small business 401(k) plans, operated by ThinkNirvana Foundation — plan administration handled by automation rather than assembled by hand.
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