tax consequences of earnout paid to qualified plan

[EGB]

Merger of two corporations (stock for stock), with possible cash earnout payments over the next few years. Some of the earnout, if earned, will be paid to shareholders' 401(k) accounts (or possibly conduit IRAs if 401(k) accounts are rolled to IRAs) based on company stock held within their accounts. Is the earnout paid to the 401(k)/IRA accounts simply considered earnings and, thus, creates no immediate tax consequence within the 401(k)/IRA? Is the answer the same if the participants sold their stock held within the 401(k)/IRA prior to the time the earnout is paid? Any thoughts are appreciated.