What Are the 403(b) Contribution Deadlines?

A 403(b) plan is a retirement savings vehicle available to employees of public schools and certain 501(c)(3) tax-exempt organizations. These plans, also known as tax-sheltered annuity (TSA) plans, allow eligible employees to contribute a portion of their salary toward retirement, with the funds growing on a tax-advantaged basis. Understanding and adhering to contribution deadlines is necessary to maximize savings and remain in compliance with tax regulations.

Employee Contribution Deadlines

The deadline for an employee to make regular elective deferrals to a 403(b) plan is the end of the calendar year, December 31. These pre-tax or Roth contributions are made through payroll deductions, with the final contribution for a given year processed with the last paycheck issued within that calendar year. Employees must set their desired contribution elections with their employer’s payroll department in time for the final pay periods of the year.

Unlike Individual Retirement Accounts (IRAs), which allow prior-year contributions until April 15, the 403(b) employee contribution deadline is firm. An employee cannot make a 2025 contribution in early 2026. All elective deferrals must be made from compensation paid during the calendar year, so any adjustments must be communicated to the employer in time to be reflected in the year’s final paychecks.

Employer Contribution Deadlines

The timeline for employer contributions to a 403(b) plan, such as matching or non-elective contributions, is more flexible. Unlike employee deferrals, employers have until their organization’s tax filing deadline for that year to deposit these funds. This includes any filing extensions the employer may have obtained.

For a tax-exempt organization that operates on a calendar year, this means it could make its 2025 employer contributions well into 2026. For many non-profits, this deadline is October 15 of the following year if an extension is filed. This extended timeframe gives employers more flexibility to calculate and fund their promised contributions. While these are the regulatory deadlines, an employer’s specific 403(b) plan document could specify an earlier date for making these contributions.

Catch-Up Contribution Rules and Deadlines

Participants in 403(b) plans have access to two distinct types of catch-up contributions, each with its own eligibility rules. The deadline for making either type of catch-up contribution is December 31, the same as the regular employee elective deferral deadline.

The first provision is the “Age 50 and Over” catch-up. Employees who are age 50 or older by the end of the calendar year can contribute an additional amount above the standard elective deferral limit. For 2025, this additional amount is $7,500. A new rule allows for a higher catch-up contribution for participants ages 60, 61, 62, and 63, who can contribute up to $11,250 if their plan allows it.

A unique feature of 403(b) plans is the “15-Year Rule” catch-up, which is not available in 401(k) plans. To be eligible, an employee must have completed at least 15 years of service with the same qualified employer, such as a public school system or hospital. Additionally, their average annual contributions in prior years must have been less than $5,000.

If these conditions are met, the employee can contribute an additional amount, which is the lesser of $3,000, a $15,000 lifetime limit, or a more complex calculation involving years of service. If an employee is eligible for both the age 50 and 15-year catch-ups, any contributions made above the standard limit are applied first to the 15-year catch-up.

Correcting Contribution Errors

An excess contribution occurs when an employee’s elective deferrals in a calendar year surpass the allowable limit, which for 2025 is $23,500, not including catch-up contributions. This can happen if an employee changes jobs and contributes to plans at both employers without monitoring the combined total.

The deadline for an employee to withdraw an excess contribution, along with any earnings it generated, is April 15 of the year following the over-contribution. If this deadline is met, the excess amount is taxed as income in the year it was contributed, but it avoids further penalties. The earnings distributed are taxed in the year they are received.

If the excess amount is not withdrawn by the April 15 deadline, it becomes subject to double taxation, as it is taxed in the year it was contributed and again when it is eventually distributed. The correction process involves the employee notifying their plan administrator, who then calculates the excess and its earnings and issues a corrective distribution.