Setting Up Expense Sheet Options 44 When adding or editing an expense code, you must specify: 1.    The name of the expense code, which users will select to categorize each expense 2.    Whether it is based on an expense rate (e.g., mileage) or a flat amount (e.g., hotel). If the expense code is based on an expense rate, you must enter the appropriate rate and the unit to which that rate applies. For example, if you are entering an expense code for mileage, the rate might be $.80 per mile. 3.    The formula to calculate the net (pre-tax) amount based on the total (see Understanding the Gross to Net Formula) 4.    The taxes which apply to expenses under that code. For each tax you assign to the expense code, you can use the default tax formula or edit it for this code. Understanding the Gross to Net Formula The “gross to net” formula instructs Web TimeSheet how to calculate backwards from the gross (total ex- pense amount) to the net (pre-tax amount) for an individual expense. Providing this formula will ensure ex- pense amounts are correct, whether the user enters the net or the gross amount for a specific expense. When entering the gross to net formula, you may enter a simple formula (useful for expenses with only one tax) or a complex, multi-level formula using parentheses to indicate precedence (useful for expenses with more than one tax). The formula may contain the following operators: Example 1 For a 7% state sales tax, the gross to net formula would be entered as $Gross/1.07. Example 2 For a 6% sales tax and a flat tax of $10.00, where the 6% sales tax is applied to the net amount before the flat tax is added, the gross to net formula would be entered as ($Gross-10)/1.06. Parentheses are used to indicate that the 10 dollars should be subtracted from the gross amount before the 6% sales tax is deducted. Choosing which Fields are Available on Expense Sheets The Expense Columns page allows you to specify which fields are valid for expense sheets entered by your users. You may want to disable any fields that are not used by your organization to prevent confusion. Operator Description + Add - Subtract * Multiply / Divide ( ) Indicates precedence $Gross Tag for the gross amount, which will be used to calcu- late the net amount When entering the gross to net formula, do not enter a currency symbol. The tax will be calculated in the currency for the expense itself, and is not necessary in the formula.