Nothing in life is simple, this holds true for 1040 with IRS
One would think that the very first step of preparing a 1040 tax return – entering taxpayer’s name, would be the simplest and most straightforward part of the prep to complete.
One’s 1040 return must report one’s name exactly as it is on file with The United States Social Security Administration (SSA).
Well, what name should one list as first, middle and last when one has multiple middle or last names?
What about a hyphen in a name?
What about those names which incorporate a mother's maiden name as part of the last name, such as in names of Spanish extraction?
What about a suffix such as Jr?
The IRS Name Control only matches the first four significant characters of an individual's last name and omits suffixes but when a suffix is reported on 1040, the IRS Name Control records it. For example Wes Kern Jr is recorded as: WES<KERN<JR
IRS in general say that as long as the first and last name match the SSN, that's all they need for processing return filings, while the middle initial or name is inconsequential (note that a 1040 return form requests only middle initial not the full middle name). When there are multiple or just one middle name only the first initial of the first middle name is used on 1040.
It’s the same story for W-7 ITIN applications and issuance.
https://www.irs.gov/irm/part3/irm_03-024-037 instructs IRS employees how to enter taxpayer names into IRS’ Name Control system.
A prudent tax return preparer will prevent confusion for a client by up-front using those guidelines when listing a 1040 or W-7 first, middle and last name.