In determining whether the material participation requirement is satisfied, no exception is made for periods during which real property is held by the decedent's estate. Additionally, contemporaneous material participation by 2 or more family members during a period totalling a year will not result in that year being counted as 2 or more years for purposes of satisfying the requirements of this paragraph (c). Death of a qualified heir (as defined in section 2032A(e)(1)) before the requisite time has passed ends any material participation requirement for that heir's portion of the property as to the origninal decedent's estate if the heir received a separate, joint or other undivided property interest from the decedent. If qualified heirs receive successive interests in specially valued property (e.g. life estate and remainder interests) from the decedent, the material participation requirement does not end with respect to any part of the property until the death of the last qualified heir (or, if earlier, the expiration of 15 years from the date of the decedent's death). The requirements of section 2032A will fully apply to an heir's estate if an election under this section is made for the same property by the heir's executor. In general, to determine whether the required participation has occurred, brief periods (e.g., periods of 30 days or less) during which there was no material participation may be disregarded. This is so only if these periods were both preceded and followed by substantial periods (e.g. periods of more than 120 days) in which there was uninterrupted material participation. See paragraph (e)(1) of this section which provides a special rule for periods when little or no activity is necessary to manage fully a farm.
26 C.F.R. §20.2032A-3