After I file a trademark application, would adding a logo have any additional charges?

Once you file your trademark application, it is not possible to perform any changes. This means you are not allowed to add any classes, items or change the wordmark/logo you initially filed. In certain situations, it is possible to amend the goods and services list, but only to a limited extent.

So, if you filed a wordmark application and would like to add a logo, you can only file a new application. This way, you will have two pending applications, one for the logo and one for the wordmark. The applications will get examined independently. If your wordmark gets dismissed by the examiner, it does not mean that your logo will be refused as well. If both marks pass the examination, you will receive two individual trademark certificates.