Kernrechtsfrage
Whether the 1979 contract included an agreement to transfer the tax burden to the respondent if tax later became due.
Extrahierter Entscheid
No such agreement was established; the parties had agreed on pricing 'free of tax' without reserving a later reimbursement claim.
Extrahierte Begründung
The cantonal court's finding of the parties' actual common intent was not arbitrary. The contractual text, annexes, and conduct showed they intended no retroactive tax transfer and simply misunderstood the tax law.