In some cases, Headliner Basic or Pro users may need to access their billing details in order to update billing details or include additional info for tax purposes. This can be done by visiting the My Plan page on your Headliner account.
From there, click view billing history in order to view your invoice/billing details. 
Next, click update information on the billing information section, in order to add your custom billing info, update the email address linked to your invoices, or to add your tax ID.