If a company is Incorporated are they required to display it on business documents/business cards/etc?

Answer 1

You should check with your state's Secretary of State.

In CA, there is no requirement, unless is it designated as a "close" corporation (fewer than 35 shareholders).

As a practical matter, you may want to include it to avoid being hassled about providing an EIN for 1099 purposes. Corporations don't receive one, and the payer may not know that it is dealing with a corporation.

Answer 2

If you have inc a company you will have to show Inc* on all your documents,like letterheads,business cards,accounts statement,Invoices on check ..