Understanding the correct format of CAF Number for eFiling tax returns

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.

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.

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.

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.

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.

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.

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.

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.

I've been through this exact same situation! Had the same confusion between 8 and B in the 8th position of my CAF number when I first got it. What helped me was looking at the context - since CAF numbers follow the 8-digit + 1-letter format that everyone's confirmed here, and since the IRS uses consistent formatting for database reasons, that 8th position has to be a number. If you're still unsure, another quick verification method is to look at any correspondence you might have received when you initially applied for your CAF number - sometimes there are multiple references to it in the same document, and one might be clearer than another. The IRS also sometimes includes a verification section in their letters that shows the format explicitly. Good luck with your client filings this season!

As someone who works in tax preparation, I can confirm what others have said about the CAF number format - it's definitely 8 numeric digits followed by 1 alphabetic character. Your instinct that the 8th position is a number (8) rather than a letter (B) is correct. One thing I'd add that might help you feel more confident: when the IRS processes CAF applications, they use automated systems that require consistent formatting. Having letters mixed in with the numeric portion would create unnecessary complexity in their database structure. The final alphabetic character serves as a check digit or classification code, but the first 8 positions are always numbers. If you're still having doubts about reading the handwritten version, you could also try calling the Practitioner Priority Service line during off-peak hours (early morning tends to be better) to get verbal confirmation. They can verify your CAF number over the phone, which might give you peace of mind before you start filing for clients.

I went through the exact same confusion last year! The handwriting on my CAF number notification was so unclear that I couldn't tell if the 8th digit was an 8 or a B either. What finally convinced me it was definitely a number was when I realized that the IRS uses sequential numbering for these identifiers - mixing letters and numbers in the main sequence would break their tracking system. If you want to be absolutely certain without calling the IRS, you can also cross-reference your CAF number with any electronic confirmations you might have received. When I submitted my initial application online through e-services, I got an email confirmation that showed the CAF number in clear digital text. Also, if you've already used your CAF number successfully on any previous filings or authorizations, that would confirm you have the right format. The 8-digit + 1-letter format is rock solid - you're definitely right that it's an 8 in that position. Better to double-check like you're doing than to have client filings get rejected over a simple transcription error!

I had a similar experience when I first received my CAF number - the handwriting was absolutely terrible and I spent way too much time squinting at it! What helped me was understanding that the IRS uses very strict formatting standards for database management purposes. The 8-digit + 1-letter format isn't just a suggestion - it's hardcoded into their systems. One thing that might give you additional confidence: if you look at the overall document layout, the IRS typically uses consistent spacing and character positioning. The 9th position (your confirmed letter) should have slightly different spacing or formatting compared to the numeric digits, which can help you visually distinguish where the number sequence ends and the letter begins. You're absolutely doing the right thing by double-checking before using it for client filings. A rejected e-file due to an incorrect CAF number can cause delays that really frustrate clients during busy season. Based on everything you've described and what others have confirmed here, you're safe going with the 8 in that position. Good luck with your filings!

Just wanted to add another verification method that helped me when I had similar CAF number confusion - if you have any clients who you've previously filed Form 2848 or 8821 for, your CAF number should be on file with the IRS from those submissions. You can actually call the Practitioner Priority Service and reference a specific client case where you used your CAF number, and they can confirm what CAF number they have on file matches what you think you have. This approach worked great for me because instead of just reading numbers over the phone (which can be prone to miscommunication), they could reference their existing records. Plus, if there was any discrepancy, they could help sort it out immediately. The key is having a specific case number or client situation to reference so they can pull up the right records quickly. The 8 numeric + 1 alpha format is definitely standard, so your instinct about the 8th position being a number is correct. But having that extra verification through existing case files can give you 100% confidence before the busy filing season really kicks into high gear!

I can definitely confirm that CAF numbers follow the 8-digit + 1-letter format that everyone has described. As someone who processes these regularly, your instinct is correct - the 8th position should be a number, not a letter. One additional tip that might help with future IRS correspondence: if you're having trouble with handwritten documents, try looking at them under different lighting conditions or angles. Sometimes the slight shadows or indentations from the writing can help distinguish between similar-looking characters like 8 and B. Also, if you have a smartphone, the magnification feature can often reveal details that aren't obvious to the naked eye. Since you're being so careful about getting this right (which is smart!), you might also want to make a clear photocopy or scan of your CAF number document once you've confirmed it. Having a high-quality digital backup can save you from having to decipher the handwriting again in the future, especially during busy filing periods when you need quick reference access.

I've been following this thread as someone who recently went through the CAF number application process myself, and I wanted to share one more verification tip that helped me. If you happen to have your original CAF application materials (Form 2848 or the online application confirmation), sometimes the IRS includes a "format example" or reference guide in the same packet that shows the proper CAF number structure. In my case, there was a small text box on page 2 of my notification letter that said something like "CAF numbers consist of 8 numeric digits followed by 1 alphabetic character" with an example format like "12345678A". Having that official format reference right in the same document gave me complete confidence when I was second-guessing my own handwriting interpretation. Also, just to echo what others have said - you're absolutely right to be cautious about this. I've seen colleagues have e-file rejections over simple CAF number errors, and it's much easier to verify it once upfront than to deal with rejected returns later. The consensus here is solid: 8 numbers + 1 letter, so that 8th position is definitely a number. Good luck with your client filings!