Let these answers help keep your diagnosis coding on track. 1. Is the diagnosis code valid for the date of service billed? 2. Is the diagnosis code limited to being reported as a secondary diagnosis only? 3. Is the diagnosis coded to the highest specificity? 4. Is additional information and/or diagnosis codes necessary? 5. Is the payer denying "unspecified" diagnosis codes? 6. Is the diagnosis code appropriate for the gender and age?