Allocating Lost Earnings

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A plan will be contributing amounts for employees who were not able to begin participation in a 401k plan w/ match as of their entry dates into the plan. This operational failure occurred in years in which the plan was valued first as a quarterly valued plan, and then also after plan switched to daily valuation. I would think that lost earnings on the contributions should be calculated/compounded on a quartely basis when the plan was valued quarterly, but what about after the plan switched to daily valuation? Can plan still calculate a quarterly rate? Monthly? Is there any requirement to do calculation on daily basis? Any guidance would be appreciated.