Need help with understanding a sentence

Hello, Would someone please help me with the following sentence, please? I got it from a letter that an accountant sent to the company I work for."We undertake to pay additional Stamp Duty (if any) payable thereon, but without prejudice to our right to appeal against your assessment of the assesed value of this share."What I don't quite understand here is the "but without prejudice to our right to appeal against your assessment of...." Does it mean that the accountant would lodge an appeal to the court if there is something wrong with the assessed share? Or it has other meanings in aacounting that I don't know about.Thanks heaps!