When a form is missing from a return the IRS sends Letter 4612C to ask you to send the missing form so they can process your return. This is very similar to Letter 12C. For old returns which have been recently filed (missing a signature) the IRS sends Letter 2416C.
Response to Letter 4612C
You probably don't need a lawyer. You may be able to use the services of TaxHelpReturns instead. They will prepare the form(s) necessary & respond to the IRS.
If you disagree with the IRS or are confused by letter please follow the Prep Steps & contact Mr. Hopkins so we can work on a solution!