In Wells Fargo & Co. v. City etc. of S. F. (1944) 25 Cal.2d 37, the court held that in allowing interest on taxes paid under protest from an incorrect date, "the court erred therefore merely as to the scope of plaintiff's recovery and its judgment is therefore not subject to collateral attack." (Id. at p. 44.) The Wells Fargo court held, in a one paragraph discussion, that the award of costs was not subject to collateral attack even if the court was without authority to require the City and County of San Francisco to pay costs. (Ibid.)