If you are writing the patient's full name on the deposit slip, it IS a HIPPA violation. An account number or 1st initial and last name would be fine though.
An example as to why it would be a HIPPA violation. Say the provider is the only STD doctor in town, you write the patient's full name on the deposit slip (and imagine it was YOUR name) and now the people at the local bank branch (who know everyone in town) saw your name........In Chicago it may not matter, or for a family doctor it may not matter, but we're talking worst case scenario.
Most HIPPA documentation says not to talk about, show, or have in writing, patient's names, using this worst case scenario sort of example.