Discount on Charge not to Exceed Specific Amount

[Brendan_Cox]

Hello,

I have a need to add a discount charge or a discount Rate Plan that can relate to a charge with conditions. The contract in question has a monthly minimum of $500, with usage beyond the $500 minimum tier. Is there a way to create a discount of 25% but stipulate that the charge will not discount to less than the $500 minimum?

For example, a charge of $1,000 would be discounted to $750,but a charge of $550 would only be discounted to the $500 minimum.

Thank you.