403(b) plans serve public schools, healthcare systems, religious organizations, and nonprofit entities. Although they share structural similarities with 401(k) plans, 403(b) plans operate under distinct regulatory rules that can create administrative complexity if not coordinated carefully.
Universal availability requirements, multi-vendor arrangements, legacy contracts, and special catch-up provisions require close coordination among payroll, HR, finance, and recordkeepers. When those functions operate in silos, compliance gaps can develop gradually and go unnoticed until audit season.
This guide outlines the core compliance requirements specific to 403(b) plans, highlights common operational risk areas, and explains how plan sponsors can maintain alignment between written documents and day-to-day administration.
If you are evaluating whether your plan has crossed audit thresholds, see our overview of when an employee benefit plan audit is required.
What Makes 403(b) Plans Different?
403(b) plans are tax-sheltered annuity plans available to public school employees, certain tax-exempt organizations, and ministers. While they are defined-contribution plans similar to 401(k) arrangements, they carry several regulatory distinctions.
Among the most significant differences are the universal availability requirement, historically decentralized vendor structures, unique contribution coordination rules, and special catch-up provisions available only to certain 403(b) participants.
These distinctions are not merely technical. They directly affect eligibility tracking, contribution administration, and audit preparation.
The Universal Availability Rule
One of the defining compliance requirements for 403(b) plans is the universal availability rule.
If a 403(b) plan permits employee salary deferrals, it must generally provide all eligible employees the opportunity to make elective deferrals, subject to limited statutory exclusions. The rule is rooted in Internal Revenue Code Section 403(b) and is strictly enforced in IRS examinations.
Improper exclusion of part-time, seasonal, or student employees remains one of the most frequent compliance errors identified in 403(b) plans. Unlike nondiscrimination testing failures in 401(k) plans, universal availability errors often require corrective employer contributions for affected employees.
Because the rule applies broadly, administrative exclusions must be reviewed carefully each year. A breakdown between HR classification and payroll processing can create exposure quickly.
When Audit Requirements Apply to 403(b) Plans
403(b) plans follow the same Form 5500 large-plan audit threshold that applies to other ERISA-covered retirement plans. Once a plan is classified as a “large plan” for reporting purposes, audited financial statements must be included with the annual filing.
Nonprofit and educational organizations often reach audit thresholds sooner than expected. Long-tenured employees and terminated participants who retain account balances can increase participant counts even when active headcount remains stable.
Participant counting rules and the 80–120 transition rule may affect classification. Sponsors should confirm filing status carefully before assuming an audit is or is not required.
For a detailed explanation of participant thresholds, transition provisions, and Form 5500 classification methodology, see our guide on when an employee benefit plan audit is required.
Form 5500 Requirements for 403(b) Plans
Most 403(b) plans must file Form 5500 annually.
Large 403(b) plans must attach audited financial statements, the independent auditor’s report, and required supplemental schedules to the filing.
403(b) audits can present unique challenges when assets are held across multiple vendors; legacy contracts remain active, or historical participant’s data is incomplete. Reconstructing accurate participant histories across vendors is often one of the most time-consuming aspects of compliance review and audit preparation.
Coordinating across vendors early in the process significantly reduces filing risk.
For filing deadlines, extensions, and penalty considerations, see our Form 5500 Filing & Audit Requirements Guide.
Contribution Limits and Special Catch-Up Rules
403(b) plans follow the same general IRS elective deferral limits that apply to 401(k) plans. However, eligible participants may qualify for age 50 catch-up contributions and, in certain cases, the 15-year service catch-up is available to specific 403(b) employers.
The 15-year catch-up provision is unique to certain 403(b) arrangements and requires careful historical tracking of prior deferrals. Improper application can result in excess contributions that require correction under IRS procedures.
Sponsors should confirm that payroll systems reflect current IRS limits, catch-up eligibility is verified accurately, and any required contribution testing is performed correctly.
Multiple Vendor Challenges
Many 403(b) plans are historically operated with multiple annuity providers. Although regulations now require stronger coordination among vendors, legacy arrangements may still exist.
Common risk areas include inconsistent hardship distribution documentation, loan limit tracking failures, incomplete asset reconciliation, and inaccurate participant census data.
When information is fragmented across vendors, audit preparation becomes significantly more complex. Consolidated reporting and consistent documentation standards are critical to maintaining compliance.
Plan Document Compliance
Since 2009, most 403(b) plans have been required to maintain a written plan document. This requirement was formalized under final Treasury regulations, and operational compliance must always align with document terms.
Sponsors should confirm that required amendments are adopted promptly; operational practices match written provisions, the SECURE Act and SECURE 2.0 updates are incorporated properly, and vendor agreements align with plan terms.
Document failures can require correction under IRS programs and may complicate audit procedures.
Common 403(b) Audit Findings
Audits of 403(b) plans frequently identify universal availability failures, eligibility tracking errors, late remittance of employee contributions, vendor coordination gaps, incomplete participant data, and inconsistencies between operational practices and written plan documents.
Many of these findings stem from decentralized administrative processes rather than intentional noncompliance. Clear documentation standards and defined internal controls significantly reduce audit findings.
SECURE Act and SECURE 2.0 Impact on 403(b) Plans
Recent legislation has expanded participation requirements and introduced additional compliance considerations for certain 403(b) sponsors.
Plan administrators should review long-term part-time employee eligibility requirements, automatic enrollment rules (where applicable), updated catch-up contribution provisions, and required amendment deadlines.
Operational updates must align with written plan amendments. If expanded eligibility has increased participation levels, sponsors should confirm whether audit thresholds have been crossed.
DOL and IRS Correction Programs for 403(b) Plans
If errors occur, 403(b) sponsors may use the same correction frameworks available to other qualified retirement plans. These may include the IRS Self-Correction Program (SCP), the Voluntary Correction Program (VCP), the Department of Labor’s Voluntary Fiduciary Correction Program (VFCP), and the Delinquent Filer Voluntary Compliance Program (DFVCP).
Correcting operational or filing errors early generally reduces financial exposure and helps preserve plan qualification.
For a closer look at available correction options, see our Correction Programs Guide for Retirement Plan Sponsors.
Preparing for a 403(b) Plan Audit
Preparation for a 403(b) audit usually starts well before the end of the plan year. Waiting until filing season often creates unnecessary pressure for payroll teams, HR staff, and recordkeepers.
A good starting point is confirming participant counts and reconciling vendor data so balances and participant histories align across systems. Sponsors should also review universal availability compliance and gather key documents such as the plan document, amendments, and fidelity bond coverage.
Because many 403(b) plans involve multiple vendors or legacy contracts, coordination with service providers matters early in the process. When communication starts sooner, it becomes much easier to avoid missing records, incomplete participant data, or last-minute documentation requests during the audit.
For an overview of the audit process and documentation expectations, see our Employee Benefit Plan Audit Services page.
What Plan Sponsors Should Keep in Mind
403(b) plans play an important role for organizations like schools, hospitals, nonprofits, and religious institutions. With that role comes a set of compliance rules that can be easy to overlook if plan administration becomes fragmented.
Universal availability requirements, multi-vendor arrangements, and ongoing legislative updates all add layers to how these plans operate. When a plan grows or administrative responsibilities shift between departments or vendors, those complexities tend to surface during compliance reviews or audits.
If your 403(b) plan is approaching audit thresholds or preparing for its first audit cycle, starting the process early usually makes things much smoother. Coordinating data, documents, and service providers ahead of time helps avoid last-minute issues during the Form 5500 filing process.
LBMC works with 403(b) plan sponsors to support audit preparation and compliance oversight, so plan administrators can move through the process with fewer surprises.
Frequently Asked Questions About 403(b) Plan Audits
What is the universal availability rule?
If a 403(b) plan permits elective deferrals, it must generally allow all eligible employees the opportunity to participate, subject to limited exclusions. Improper exclusions often require corrective employer contributions.
How are 403(b) plans different from 401(k) plans?
Both are defined-contribution plans, but 403(b) plans come with a few unique rules. The universal availability requirement, special catch-up provisions, and the way many plans still work with multiple vendors can make administration more complicated than a typical 401(k).
What are common 403(b) compliance mistakes?
Frequent issues include universal availability failures, inaccurate eligibility tracking, late employee contribution deposits, incomplete vendor coordination, and inconsistencies between operational practices and written plan documents.
Do all 403(b) plans require an audit?
Not all plans require an audit. Audit status depends on participant counts and Form 5500 classification. For a full explanation of thresholds and counting rules, see our guide on when an employee benefit plan audit is required.
