IRS Publication 5592 – Large Business and International (LB&I) taxpayers and their representatives now rely on secure digital tools to streamline IRS audits. IRS Publication 5592 (Rev. April 2022) delivers official, practical troubleshooting guidance for the Taxpayer Digital Communication Secure File Sharing – Secure Messaging (TDC SFS-SM) system.
This free IRS resource helps users quickly resolve login issues, verification code problems, password resets, and email conflicts so audit communications stay secure and on track.
Download the official PDF here: IRS Publication 5592 (Rev. 4-2022).
Still current as of February 2026 (no newer revision exists; cross-referenced in later IRS publications such as Pub 5896), Publication 5592 remains the go-to guide for LB&I audit participants using TDC SFS-SM.
What Is TDC SFS-SM and Why Does IRS Publication 5592 Matter?
TDC SFS-SM stands for Taxpayer Digital Communication Secure File Sharing – Secure Messaging. It is the IRS’s dedicated secure portal that allows LB&I agents to exchange messages and files with taxpayers and authorized Power of Attorneys (POAs) during audits—without email, regular mail, or insecure attachments.
IRS Publication 5592 explains exactly how to:
- Complete the required IRS Secure Messaging Taxpayer Consent Form
- Set up and access your account
- Handle the most common technical hurdles
- Reply securely to agent messages
Using TDC SFS-SM reduces delays, protects sensitive data, and supports the IRS’s paperless initiative for large and international businesses.
Who needs this guide?
- Corporations and partnerships under LB&I audit
- Authorized Power of Attorneys (Form 2848) representing LB&I taxpayers
- Employees or officers who sign on behalf of the company
Step-by-Step: Getting Started with TDC SFS-SM (From IRS Pub 5592)
- Receive and Complete the Consent Form
Your LB&I agent sends the IRS Secure Messaging Taxpayer Consent Form. Complete it legibly with:- Full taxpayer or company name
- SSN or EIN
- Authorized contact names, emails, and phone numbers
Designate a primary contact.
Sign and return via in-person, email, e-fax, or mail.
- Authentication for Remote Users
If no prior face-to-face meeting occurred, complete a one-time video authentication using an IRS-approved platform (Cisco WebEx, ZoomGov, or Microsoft Teams). - SADI Account Email Conflict Resolution
The Secure Access Digital Identity (SADI) system and TDC SFS-SM each allow only one email per account.
Solution (exact steps from Pub 5592):- Log into your IRS online account at IRS.gov
- Go to Profile → Edit User Profile → Change email to a personal address
- Update, log out, then log back into Secure Messaging to sync
- Notify your LB&I agent of the change
Account Creation and First Login – Detailed Troubleshooting
After the IRS creates your account you receive an email with your username and portal link. Follow these exact steps (Publication 5592):
Initial Password Setup
- Click the link in the account creation email
- Enter your Secure Messaging User ID
- Confirm your partially masked email
- Enter the 6-digit verification code from [email protected] (valid 30 minutes)
- Create a strong password (must be changed every 60 days)
- Receive confirmation
Common Issue: Verification code never arrives
Pub 5592 Fixes:
- Check junk/spam folders (add [email protected] to safe senders)
- Check Deleted Items
- Ask IT to whitelist [email protected] (firewalls often block it)
Common Issue: “User not recognized” during setup
Fix: Contact your LB&I agent immediately to verify username and email.
Daily Use: Logging In and Replying to Messages
New Message Alert
You receive: “You Have a New IRS Secure Message Waiting.”
Click the link or go directly to: https://www.irs.gov/help/lbi-secure-messaging
Login Process
- Enter username and password
- Accept Terms of Service
- Enter fresh verification code from [email protected]
- Access Inbox (you cannot start new conversations—only reply)
Replying (6-step process from the publication):
- Log in → Click Inbox
- Left-click the message to open
- Download/save any attachments via your browser
- Click Reply
- Type message and attach files if needed
- Click Send
Top Troubleshooting Tips Straight from IRS Publication 5592
| Issue | Symptoms | Official Solution (Pub 5592) |
|---|---|---|
| No verification code | Code email missing | Whitelist [email protected]; check spam/deleted; reboot router; contact IT |
| Cannot log in | “Invalid credentials” after correct password | Clear browser cache & cookies; reboot computer; try different browser |
| Password expired/locked | After 60 days or failed attempts | Use reset link: https://connect.irs.gov/adssp/accounts/authVerify?operation=reset; wait 120 minutes after lockout |
| SADI vs TDC email conflict | Account creation fails | Switch SADI to personal email using the 11-step profile edit process |
| Attachments won’t open | Browser blocks download | Right-click → Save As or use different browser |
| Username not recognized | System says email unknown | LB&I agent must confirm or correct your username/email |
Pro Tip: Always use a modern browser (Chrome, Edge, Firefox) and keep it updated. Corporate firewalls are the #1 blocker—coordinate with your IT team early.
Best Practices for LB&I Audits Using TDC SFS-SM
- Respond promptly—delays can extend audit timelines
- Use the primary contact for all system-related questions
- Never share your TDC username/password
- Keep a record of every message sent/received (the portal archives them)
- POAs who are not company employees receive separate accounts—check the POA box on the consent form
Related Official Resource: Pair Publication 5592 with IRS Publication 5593 (FAQs for LB&I Audits – TDC SFS-SM) for additional answers.
Frequently Asked Questions (FAQ)
Q: Is TDC SFS-SM mandatory for LB&I audits?
A: It is the IRS-preferred method once your agent invites you.
Q: Can I use my personal email?
A: Yes—many taxpayers route business email to TDC and personal email to SADI.
Q: What if I lose my username?
A: Your LB&I agent is the only one who can confirm or reissue it.
Q: Is the system still supported in 2026?
A: Yes—Publication 5592 remains the current official troubleshooting guide with no superseding revision posted on IRS.gov.
Conclusion: Master TDC SFS-SM and Keep Your LB&I Audit Moving
IRS Publication 5592 removes the frustration from secure digital audit communications. By following its clear, step-by-step troubleshooting instructions, taxpayers and POAs can resolve 95% of technical issues in minutes—without calling the agent for every login glitch.
Action Steps Today:
- Download IRS Publication 5592 (PDF)
- Bookmark the Secure Messaging portal: https://www.irs.gov/help/lbi-secure-messaging
- Whitelist [email protected] in your email system
- Share this guide with your tax team and IT department
For complex audit situations, always consult your enrolled agent, CPA, or tax attorney familiar with LB&I procedures.
Official Source: All information above is taken directly from IRS Publication 5592 (Rev. April 2022) and current IRS.gov listings. Always verify the latest version at IRS.gov/forms-pubs.
Keywords: IRS Publication 5592, LB&I audit troubleshooting, TDC SFS-SM, IRS secure messaging, LB&I secure file sharing, IRS TDC login issues, LB&I audit digital communication.
Stay compliant, stay secure—use the official IRS tools designed for large business audits.