The director of revenue is authorized to abate the unpaid portion of the assessment of any tax or any liability in respect thereof, which

1. (1) Is excessive in amount, or
2. (2) Is assessed after the expiration of the period of limitations properly applicable thereto, or
3. (3) Is erroneously or illegally assessed.

(L. 1972 S.B. 549)

Effective 1-1-73, see § 143.109