The gross to net formula determines how Replicon calculates the net amount (pre-tax) from the total expense amount employees enter. You should define it for expense codes so that net expense amounts can be calculated when users enter gross amounts. Replicon doesn't create this formula automatically since, with multiple taxes, it can't determine in what order taxes are applied.

Use the $Gross variable to represent the gross amount. For example, if you are defining an expense code for airfare that includes tax codes for airport tax ($10.00 flat tax) and GST (5%), and the GST is not taxed on the airport tax, the gross to net formula for the expense code would be: ($Gross-10)/1.05

Gross to Net formula

Refer to Understanding the Gross to Net Formula in Replicon's online help for more information.

Note:
To know more about, how the gross to net formula is calculated in expenses, please use the following KB article.
http://www.replicon.com/customer-zone/kb-3410