
401(k) glossary
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Administration
Plan conversion and deconversion
Short definition
A plan conversion moves an existing 401(k) plan from one recordkeeper to another. Deconversion is the outgoing provider’s side of the same move: closing its records and transferring the plan’s assets and data.
What a plan conversion is
The plan itself continues. It keeps its history, its participants and their vesting, and gets a new provider. The usual steps are: give notice to the current provider, sign with the new one, restate the plan document, map the old investments to new ones, send participants a blackout notice, transfer assets and records, and reconnect payroll.
Why it matters to employers
Choosing and changing a provider is a fiduciary decision, so keep a record of why you made it. If participants will be unable to direct investments or take loans and distributions for more than three consecutive business days, the plan administrator must give a blackout notice 30 to 60 days in advance. Moving at the start of a plan year keeps one provider responsible for that year’s testing and Form 5500.
Example
A company signs with a new provider in September for a January 1 start. Employees receive the blackout notice in November, assets move at year end, and accounts open at the new provider in January with balances, loans and vesting history loaded.
Common mistakes
Terminating the plan when you only meant to change providers. That forces full vesting and can trigger the successor plan rule.
Sending the blackout notice late or not at all.
Not collecting prior-year test results, loan records and vesting data from the old provider.
Not checking the old contract for notice periods.
Basic Capital and this term
When a plan moves to Basic Capital, Basic Capital sends the transfer notice and manages the blackout.
Go deeper
Read the full employer guide related to: Plan conversion and deconversion
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Sources
eCFR (National Archives): 29 CFR 2520.101-3: Notice of blackout periods under individual account plans (https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XXV/subchapter-C/part-2520/subpart-A/section-2520.101-3), retrieved 2026-11-11 U.S. Department of Labor, EBSA: Meeting your fiduciary responsibilities (https://www.dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/meeting-your-fiduciary-responsibilities), retrieved 2026-11-11
General information, not legal or tax advice.

