3824547 - What are the Taxability & Deductibility and How is taxable and deductible amounts calculated in Concur?

We find on some reports these entry fields have data, but we don't know how the system calculates. Could you provide us formula and how to maintain it?

Custom 31-Taxable/Deductible Amount
Custom 32-Non-Taxable/Non-Deductible Amount
Custom 33-Tax Deductible VAT Amount
Custom 34-Non-Tax Deductible VAT Amount

Calculation formula for custom 31 to custom 34 when enabled Taxability and Deductibility. , KBA , CON-EXP-ADM-TAX , Tax Administration , Problem