In actions brought to recover the balance due upon a mutual and open account current the cause of action shall be deemed to have accrued at the time of the last item proved in such account.
Wis. Stat. § 893.64
There must be mutual debts or setoff before this section applies. Estate of Demos, 50 Wis. 2d 262, 184 N.W.2d 117 (1971).