First effective during the plan year, but not effective as of the beginning of the plan year.

Effective as of the beginning of the plan year, but adopted after the beginning of the plan year. (For example, an increase of matching contributions implemented mid-year but retroactive to the beginning of the plan year).

Notice at least 30 days (and not more than 90 days) before the effective date of the change, unless not practical (in which case, no later than 30 days after the adoption date). An updated safe harbor notice that describes the mid-year change and its effective date must be provided to affected employees least 30 days (and not more than 90 days) before the effective date of the change (see Practice Note, Safe Harbor 401(k) Plans: Overview and Planning Opportunities: Employee Notice Requirements). If it is not practicable for the updated safe harbor notice to be provided before the effective date of the change (if there is a mid-year change to increase matching contributions retroactively for the entire plan year, for example), the notice is treated as provided timely if it is provided as soon as practicable, but not later than 30 days after the date the change is adopted.

A 30-day election period before the effective date of the change, unless not practical (in which case, an election period that ends no later than 30 days after the adoption date). Each affected employee must be given a reasonable opportunity (including a reasonable period after receipt of the updated notice) before the effective date of the mid-year change to change his cash or deferred election (or any after-tax employee contribution election). If a 30-day election period is not practicable before the effective date of the change, this requirement will be deemed satisfied if the election opportunity begins as soon as practical after the date the updated notice is provided and no later than 30 days after the adoption date of the change.

An increase in the number of completed years of service required for an employee to have a nonforfeitable right to the employee's account balance attributable to safe harbor contributions for a qualified automatic contribution arrangement (QACA) under the safe harbor rules located in 26 C.F.R. Sections 1.401(k)-3(k)(3) or 1.401(m)-3(a)(2) (see Standard Document, Safe Harbor Notice for Qualified Retirement Plans with Optional QACA Provisions: Drafting Note: Qualified Automatic Contribution Arrangement (QACA)).

A reduction in the number of employees eligible to receive safe harbor contributions or otherwise narrowing of the group, unless the reduction was a permissible change under eligibility service crediting rules or entry date rules made for employees who are not already eligible to receive safe harbor contributions (as of the date the change is either made effective or is adopted).

A change to the type of safe harbor plan, such as a change from a traditional 401(k) safe harbor plan to a QACA 401(k) safe harbor plan.

The modification or addition of a formula to determine matching contributions (or the definition of compensation used to determine matching contributions) that increases the amount of matching contributions, or a change that permits discretionary matching contributions. However, this mid-year change is permitted if it is made retroactively effective for the entire plan year (which may require a plan that provides for periodic matching contributions as described in 26 C.F.R. Sections 1.401(k)-3(c)(4) and 1.401(k)-3(c)(5)(ii), or 1.401(m)-3(d)(4), to be amended to provide for matching contributions based on the entire plan year) and at least three months before the end of the plan year: