An insurance audit created an additional bill for premium to my company. That audit covered a period between November 2016 and march 2017. A CPA firm completes the owners taxes for the company and has already completed taxes for 2016 and 2017. The company is an LLC so going back to allocate this cost correctly would require a great deal of effort and cost on the part of the CPA firm. This event seems to take place every year. Best methods to handle this cost?