We require that tax professionals and others who want to use IRS e-file become certified as IRS Authorized e-file Providers. Depending on your business model and capabilities, you can choose to become certified in one or all of the following roles.

Electronic Return Originators (EROs) — begin the electronic transmission of returns to the IRS. The ERO may have prepared returns for clients or have collected returns from taxpayers who have prepared their own.
Intermediate Service Providers — process tax return data, typically from an ERO or an individual taxpayer, and forward to a transmitter.
Transmitters — have software and modems that connect with the IRS computers. Transmitters are authorized to send tax return data directly to the IRS.
Online Providers — are a type of transmitter that sends returns filed from home by taxpayers using tax preparation software to file forms 990, 1040, 1120 and/or 1120POL...
Software Developers — write the e-file software programs that follow IRS specifications for e-file.
Reporting Agents — an accounting service, franchiser, bank or other person that is authorized to e-file Form 940/941 for a taxpayer.

You are in the best position to decide which of these options makes the most business sense for you and list those on your application.