If you charge your clients based on the total spend. You need to add your margin to all the cost metrics. The margin can be added on an account level. Here are the steps you need to follow to add margin to an adwords account
1. Navigate to Accounts page using the "Accounts" link in the left sidebar
2. You will see a list of accounts that have been linked. Please find your mcc account from this list and click on it
3. In this page you will see a list of accounts that are under your mcc.
4. Click on the edit button(pencil icon) against any account from the list.
5. This will show you the account edit page. In this page you can enter the margin in % for the account as show below
Note: Adding a margin to your account will affect all your reports and dashboards.
If you have any questions regarding margin please drop us an email at firstname.lastname@example.org