BILLING BACK CHARGES

Hello

As part of our billing process, we often need to "back charge" our client for expenses we have incurred on their behalf.  When this happens I currenlty pay the invoice as per "normal" then when it comes to bill the client, when we raise our invoice for the services we provide we may also need to add for example -  "Offsite laundry"  $650.00; labour, general expenses, etc.   On the invoice we are raising for them the "back charge" item is entered under  the accounts list category "income".  The problem with this is that it is then recorded under "income" when the P&L is done and it's not really "income" it's more of a reimbursement.  What's the best way to record these "back charges" ?

Thanks

Lisa_H