It is not possible to look up a provider's electronic filing identification number, as the IRS warns providers against sharing their EFINs with others, explains the Internal Revenue Service. Tax professionals can use the provider locator service on IRS.gov to verify that a provider is e-file authorized, as of 2016.
To verify that a provider is e-file authorized, select the provider type from the drop-down menu on the provider locator service, instructs the IRS. Then, type the first three or four digits of the provider's ZIP code, or enter all five digits. Entering three or four digits allows for searching within a broader geographic range, while entering all five digits of the ZIP code narrows the search.
A provider is not even allowed to share its EFIN for the purpose of transferring ownership of the business to another entity, notes the IRS. If there is any indication that a provider's EFIN has been compromised, the IRS issues that provider a new number.