What is an EFIN?
Electronic Filing Identification Number
Short answer
An EFIN is the IRS number a firm receives when it is accepted into the IRS e-file program. Without one, the firm cannot e-file client returns.
What it is
An EFIN (Electronic Filing Identification Number) is the six-digit number the IRS assigns to a firm or sole practitioner that has applied to the IRS e-file program and passed its suitability check. The check covers the principals of the firm: tax compliance, credit history and, for most applicants, fingerprints and a background check.
The EFIN belongs to the firm, not to the software. One number generally covers one office location, and it cannot be sold or lent. The IRS expects the holder to keep it confidential and to report any misuse, because a stolen EFIN lets a thief file fraudulent returns under the firm's name.
Why it matters for a tax firm
The EFIN is the licence to e-file. Losing it, or having it suspended after a data breach, stops the firm from filing in the middle of a season. The application takes weeks, so new firms apply well before January.
How XyloDocs handles it
XyloDocs holds an EFIN as an Authorized IRS e-file Provider, accepted by the IRS as both Software Developer and Transmitter. Its own tax software is planned for the 2027 season; the communication platform firms use today does not file returns.
Related terms
Read more on XyloDocs
Sources
Questions about EFIN
Does every preparer in the office need an EFIN?
No. The firm holds the EFIN; each preparer needs their own PTIN. A firm with several offices may need an EFIN for each location.
How long does an EFIN application take?
The IRS says to allow about 45 days, and longer if fingerprints or extra review are needed. Apply in the autumn if you want to e-file in January.
Can an EFIN be stolen?
Yes. Criminals file fake returns under stolen EFINs. Keep it off emails and shared documents, check your e-file application summary for unexpected volume, and report misuse to the IRS.
Last reviewed: October 16, 2026. This glossary explains terms; it is not legal or tax advice. Check the cited source for the current rule.
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