Official-source directory
Find the right fax route before you send
These entries connect a specific document and routing rule to the official source that publishes the fax number. Open an entry to see its scope, warnings, and a send form with the number prefilled.
Checked 2026-07-23
Each entry links to the IRS page or PDF used for verification.
Verify before every transmission
Government routing rules and fax numbers can change without notice.
Available countries
Important limitation
A public contact fax number is not automatically a filing number. This directory only publishes routes where the cited instructions identify both the document and the destination. It is independent and is not affiliated with any listed organization.