Tax not being added to COD Shipments

When we ship a package COD the total cost of the COD does not include the tax on the package. So we are having customers just pay the COD cost, but that is leaving them with a balance since tax on the item is not included. Does anyone know what might need to be done to fix this? Thanks.

That is happening to all customer or only to a few?

Are you using E-Ship?

From what I know it happens to all customers and yes we are using E-Ship. I have instructions on a work around, but I am not a fan of that when it should work correctly.