ORS § 308A.122
If during the period specified in ORS 308A.119, the farmland again meets the gross income or other requirements of ORS 308A.071, the owner may apply to the assessor on or before April 1 of the next calendar year, in the manner provided in ORS 308A.077, for farm use special assessment. If satisfied that the requirements of ORS 308A.071 have been met, the assessor shall restore farm use special assessment to the land. The potential additional taxes for all years not already abated under ORS 308A.119 shall continue as a potential liability against the land under ORS 308A.119 and 308A.706, except that each oldest year of potential liability shall abate as the total of all other years of potential additional tax liability for prior years reaches five.
ORS 308A.122