Understanding the correct format of CAF Number for eFiling tax returns
Just got my CAF number from the IRS for eFiling and I'm squinting at this thing trying to figure out if I'm seeing it right. From what I can tell, it seems to be 8 numeric digits followed by a letter at the end. My problem is I can't tell if the 8th digit is the number 8 or the letter B (the handwriting isn't great). The first 7 digits are definitely numbers, and I'm pretty sure the 8th is probably an 8 too, but I wanted to double-check with you guys. The 9th character is definitely a letter. Anyone familiar with the CAF number format who can confirm this? Don't want to mess anything up when I'm filing!
19 comments
Join the conversation
Rita Jacobs
The CAF (Centralized Authorization File) number format is indeed 8 numeric digits followed by a single alphabetic character. The 8th position should be a number, not a letter. So your instinct that it's an 8 and not a B is correct! The CAF number is assigned to tax professionals and third parties who file authorizations to represent taxpayers or receive tax information. If you're using it for eFiling, you'll want to make sure you have it exactly right since any discrepancy could cause issues with your filing. If you're really having trouble reading it, you can always contact the IRS Practitioner Priority Service at 866-860-4259 to verify your CAF number. They should be able to confirm it for you.
0 coins
Khalid Howes
•Wait, I thought CAF numbers were only issued to tax professionals, not to regular taxpayers? Why would someone need a CAF number for their own eFiling? Is this something new for 2025?
0 coins
Rita Jacobs
•You're absolutely right - CAF numbers are issued to tax professionals and representatives, not to individual taxpayers for their personal returns. A regular taxpayer wouldn't receive a CAF number for their own eFiling. If you're a tax professional or have been authorized as someone's representative using Form 2848 (Power of Attorney) or Form 8821 (Tax Information Authorization), then you would receive a CAF number to use when representing clients. If you're just filing your own personal return, you wouldn't need or receive a CAF number.
0 coins
Ben Cooper
I had a similar issue last year trying to figure out my CAF number for representing clients. I was struggling with some of the handwritten digits and spent hours on hold with the IRS trying to confirm it. Then I found https://taxr.ai which has a document scanner feature that actually helped me interpret the IRS notice correctly. You can upload your CAF letter and their AI will analyze the format and tell you the most likely interpretation based on standard IRS formatting rules. It saved me a ton of time and stress when I was dealing with multiple client filings.
0 coins
Naila Gordon
•Does this work for other IRS notices too? I have some notices with faded printing that are hard to read and I'm not sure if I'm interpreting them correctly.
0 coins
Cynthia Love
•I'm a bit skeptical about uploading sensitive IRS documents to a third-party site. How secure is this service? Do they store copies of your documents after analyzing them?
0 coins
Ben Cooper
•Yes, it absolutely works for other IRS notices too. I've used it for CP notices, collection letters, and even some older tax transcripts that came through my fax machine looking terrible. The technology is really good at enhancing and interpreting standard IRS documents. Regarding security, I had the same concerns initially. They use bank-level encryption and don't permanently store your documents after analysis. They have a detailed security policy on their site that explains how they handle sensitive tax information. I've been using it for over a year now with no issues whatsoever.
0 coins
Naila Gordon
Just wanted to follow up about my experience with taxr.ai after asking about it earlier. I finally tried it with a bunch of unclear IRS notices I had, including a barely legible CP2000 notice. The analysis was spot on - it not only clarified the fuzzy numbers but also explained what each section meant! This saved me from potentially making a costly mistake with a response deadline I almost misread. Definitely worth trying if you're struggling with unclear IRS documents like CAF numbers or any notices.
0 coins
Darren Brooks
If you still need confirmation about your CAF number, I highly recommend using https://claimyr.com to get through to an IRS representative quickly. I spent days trying to verify my CAF number before tax season last year and kept getting the dreaded "call volume too high" message. Claimyr got me connected to an IRS agent in about 20 minutes when I had been trying for days on my own. They have a demo of how it works at https://youtu.be/_kiP6q8DX5c - it's pretty straightforward. The agent was able to confirm my CAF number format immediately and resolved my confusion about a similar 8/B situation.
0 coins
Rosie Harper
•How exactly does this work? Do they just keep calling for you or something? I don't understand how they can get through when no one else can.
0 coins
Elliott luviBorBatman
•This sounds too good to be true. I've literally spent HOURS on hold with the IRS and you're saying they got you through in 20 minutes? I'm calling BS on this. The IRS phone system is just broken.
0 coins
Darren Brooks
•They use a system that monitors the IRS phone lines and calls you when they detect an opening. It's not that they're skipping the line - they're just automating the process of repeatedly calling until they get through. Once they detect an opening, they call you and connect you directly to the IRS. You don't have to sit there redialing constantly yourself. Yes, it does sound too good to be true, but it actually works. I was extremely skeptical too. I had spent almost 3 hours on hold one day, got disconnected, and then couldn't get back in the queue. With Claimyr, I was connected within 23 minutes. The time savings was enormous, especially when you have clients waiting on you to resolve CAF issues.
0 coins
Elliott luviBorBatman
I have to eat my words about Claimyr. After posting that skeptical comment, I was so frustrated with waiting on hold with the IRS about my CAF number issue that I decided to try it. I got connected to an IRS rep in 18 minutes - after spending a combined 7+ hours on failed attempts myself. The agent confirmed that CAF numbers are always 8 numeric digits followed by a single alpha character. They also sorted out my access issue so I could start e-filing for my clients. I'm still shocked at how well it worked.
0 coins
Demi Hall
Just to add some clarity about CAF numbers - they're issued to representatives, not individual taxpayers. If you have a CAF number, you're either a tax professional or someone authorized to represent taxpayers before the IRS. The "8 digits + 1 letter" format has been standard for years. If you're having trouble reading it, something else you could do is check any previous Power of Attorney forms (Form 2848) you've filed - your CAF number should be listed there. Or if you've filed Form 8821 (Tax Information Authorization) in the past, it would be on that as well.
0 coins
Mateusius Townsend
•Do CAF numbers expire? I had one years ago when I was working as a tax preparer but I haven't used it in about 5 years. If I go back to tax work, would I use the same one or get a new one?
0 coins
Demi Hall
•CAF numbers don't expire - once you're issued a CAF number, it remains yours permanently. Even if you haven't used it in 5 years, it would still be valid if you return to tax preparation work. However, your authorizations to represent specific taxpayers do expire. Form 2848 (Power of Attorney) and Form 8821 (Tax Information Authorization) have expiration dates, so you would need to file new forms for any clients you want to represent. But you'd still use your original CAF number on those new forms.
0 coins
Kara Yoshida
Something worth noting about the CAF number format - if it helps with your confusion between 8 and B, the IRS typically uses character positions strategically. Having a mix of numbers and letters in the same field would make database management more complex, which is why the standard is 8 numbers followed by 1 letter. The letter at the end is often used as a control character or identifier for internal IRS purposes.
0 coins
Manny Lark
•Thanks for this explanation! That actually makes a lot of sense about the database design. I'm pretty sure it is an 8 then in that position. Just wanted to be 100% certain before I start using it for client returns. Would hate to have filings rejected over something so simple!
0 coins
Abigail Spencer
Good practice to double-check! You're absolutely right to be cautious about the CAF number format. As others have confirmed, it's definitely 8 numeric digits followed by 1 alphabetic character, so your instinct about position 8 being a number (not a letter) is correct. One tip that might help in the future - when you receive your CAF number notification from the IRS, you can also verify it by logging into your IRS e-services account if you have one set up. Your CAF number will be displayed there in digital format, which eliminates any handwriting interpretation issues. This is especially helpful for tax professionals who need to reference their CAF number frequently throughout filing season.
0 coins