WHAT IS THE RETENTION PERIOD FOR REG CC HOLD NOTICES?

You need only retain copies of notices of holds imposed under §229.13(e) (reasonable cause to doubt collectibility). The retention period is two years from the date of the notice under 229.21(g), where you should look for some clarifying language.

Holding on to any other holds notices is counterproductive, since it increases your exposure in examinations and audits.