(1) A party filing an appeal with the board must elect either a formal or an informal proceeding, according to rules of practice and procedure adopted by the board. If no such election is made, the appeal must be treated as an election for an informal proceeding: PROVIDED, That nothing prevents the assessor or taxpayer, as a party to an appeal pursuant to RCW 84.08.130, within 20 days from the date of the receipt of the notice of appeal, from filing with the clerk of the board notice of intention that the hearing be a formal one: PROVIDED, HOWEVER, That nothing herein may be construed to modify the provisions of RCW 82.03.190: AND PROVIDED FURTHER, That upon an appeal under RCW 82.03.130(1) (c), (d), (e), (h), (i), or (j), the director of revenue may, within 10 days from the date of its receipt of the notice of appeal, file with the clerk of the board notice of its intention that the hearing be held pursuant to chapter 34.05 RCW.

(2) A responding party may file a cross appeal. In the event that appeals are taken by different parties from the same decision, order, or determination, and only one party elects a formal proceeding, the appeal must be conducted as a formal proceeding.