What Is the Reference ID Number on Form 5472?

In short:

• The reference ID number on Form 5472 is an alphanumeric identifier established by or on behalf of the reporting corporation to uniquely identify a 25% foreign shareholder or related foreign party.
• It is required only when the foreign shareholder has no U.S. identifying number (such as an SSN, ITIN, or EIN), though filers are permitted to provide both an EIN and a reference ID number.
• You do not apply to the IRS for it: your company assigns it (up to 50 characters, letters and numbers only, no spaces or special characters) and must use it consistently year after year.

What is the reference ID number?

According to the IRS Instructions for Form 5472, a reference ID number is an identification number established by or on behalf of the reporting corporation identified in Part I. It is assigned to 25% foreign shareholders and/or related foreign parties with respect to which Form 5472 reporting is required.

These numbers are used to uniquely identify the 25% foreign shareholder or related foreign party in order to keep track of that foreign person from tax year to tax year.

What to enter on Form 5472

When completing Part II of Form 5472, specific rules govern where and how this number is reported:

• Where to enter it: Enter the shareholder's reference ID number on lines 4b(2), 5b(2), 6b(2), or 7b(2) for each 25% foreign shareholder listed in Part II, if required.
• When it is required: A reference ID number is required only in cases where no U.S. identifying number was entered on the preceding line (lines 4b(1), 5b(1), 6b(1), or 7b(1)). For individuals, a U.S. identifying number means a Social Security Number (SSN) or an Individual Taxpayer Identification Number (ITIN) issued by the IRS. For all other entities, it means an Employer Identification Number (EIN).
• Entering both numbers: Filers are explicitly permitted to enter both an EIN and a reference ID number. If applicable, enter the reference ID number you have assigned to the 25% foreign shareholder.
• Format and characters: The reference ID number must be alphanumeric, meaning it can be alphabetical, numeric, or any combination of the two. No special characters or spaces are permitted.
• Character limit: The length of a given reference ID number is limited to a maximum of 50 characters.
• Year-to-year consistency: The same reference ID number must be used consistently from tax year to tax year with respect to a given 25% foreign shareholder or related foreign party.
• No reuse of retired numbers: If for any reason a reference ID number falls out of use (for example, if the 25% foreign shareholder or related foreign party no longer exists due to disposition or liquidation), that reference ID number cannot be used again for another 25% foreign shareholder or related foreign party for purposes of Form 5472 reporting.
• Mergers and acquisitions: the IRS gives this example: if a 25% foreign shareholder or related foreign party is involved in a merger or acquisition, the filer must use a reference ID number that correlates the previous number with the new one assigned to that party.

What you should not assume

• Do not assume you need to request a number from the IRS: Because reference ID numbers are established by or on behalf of the reporting corporation filing Form 5472, there is no need to apply to the IRS to request a reference ID number or to ask for permission to use these numbers.
• Do not assume spaces or symbols are allowed: the IRS says no special characters or spaces are permitted. Use letters and numbers only.
• Do not assume you can reassign an old number: You cannot recycle an existing number for a new shareholder or related party, even if the former owner liquidated or sold their interest.
• Do not assume it is always mandatory: If an individual foreign shareholder has an SSN or ITIN, or an entity has an EIN entered on the preceding line, a reference ID number is not required (although entering both an EIN and a reference ID number is allowed).

When to ask for help

Assigning tax identifiers and maintaining year-over-year consistency is essential to avoid reporting discrepancies. You should consider asking for assistance if:

• You need to determine whether a foreign owner or related party needs an ITIN, an EIN, or an internal reference ID number.
• You are unsure how to correlate a new reference ID number with a previous one after a merger, acquisition or ownership change.
• You are establishing Form 5472 reporting for the first time and want to ensure your record-keeping and shareholder tracking meet IRS requirements across future filings.

What Melya does / does not do

To keep expectations clear and transparent, here is what Melya does and does not do:

• What Melya does:
  • We prepare US tax documents (such as Form 5472 and pro forma Form 1120) for non-US owners of US LLCs.
  • We prepare your returns for your signature and fax them to the IRS with a transmission receipt confirming sending.
  • We provide transparent, fixed-price services with clear scopes of work.
• What Melya does NOT do:
  • We do not provide legal advice.
  • We do not provide tax advice regarding your country of residence (such as France or Switzerland); you should consult a qualified local professional in your jurisdiction for home-country obligations.
  • We do not represent clients before the IRS. Melya’s founder holds an IRS PTIN (Preparer Tax Identification Number) and is not a CPA, Enrolled Agent (EA), CAA, or attorney.
  • We do not electronically file (e-file) Form 5472 and pro forma Form 1120, as the IRS requires foreign-owned domestic disregarded entities to submit these forms by fax or mail.
  • We do not claim that the IRS "accepts" or "acknowledges" a filing based on transmission (a fax transmission report proves delivery/sending, not acceptance), nor do we guarantee penalty relief or specific outcomes.

Ready to verify your US LLC filing requirements?

If you are unsure which forms, tax IDs, or filing rules apply to your US LLC, start with our Diagnostic for First-Time Filers / Not Sure Yet at $149:

• Covers 5 complete assessments (Form 5472, Form 1040-NR, W-8 or W-9 form determination, sales tax nexus check, and Form 1099-NEC assessment) delivered in writing within 24 to 48 hours.
• The $149 diagnostic fee is credited directly toward any filing preparation work if you proceed within 30 days.