S-Corp DIY Taxes - Can I File Form 1120-S by Mail Instead of E-Filing?

Yes, you can absolutely file a paper Form 1120-S for your S-Corporation, but there are some important things to know. The IRS generally requires e-filing for corporations with assets of $10 million or more, or businesses that file 250 or more returns annually. It sounds like your single-member S-Corp falls well below these thresholds, so paper filing is perfectly acceptable. Just make sure you're using the correct 2024 tax year forms (for filing in 2025), include all required schedules and attachments, and don't forget to also complete Form K-1 for yourself as the shareholder. Mail everything to the correct IRS address for your location - this is super important as sending it to the wrong processing center can delay things significantly. One tip I'd suggest - even though you're saving on e-filing fees, consider using tax software to prepare the forms and then just print them out. This helps minimize calculation errors which are common when completing these forms manually.

I was in your exact situation last year and found an amazing solution! After spending hours trying to figure out all the S-Corp tax forms myself, I found this service called taxr.ai (https://taxr.ai) that actually guided me through the entire 1120-S process. It was WAY cheaper than hiring a CPA but gave me the confidence that I was filing correctly. What I liked most was that you could upload your financial documents and it would help identify potential deductions I was missing. They have specific S-Corporation support that walks you through all the forms, including the K-1 allocation. I ended up printing and mailing my return to avoid the e-filing fee just like you're considering, and everything went smoothly. The IRS processed it without any issues in about 5 weeks.

Just wanted to follow up - I ended up trying taxr.ai after reading about it here and it was exactly what I needed! The interface really is straightforward like you said. I was able to complete my entire S-Corp return in one evening, which I honestly didn't think was possible. The step-by-step guidance for allocating business expenses was super helpful, and it flagged a home office deduction I was calculating incorrectly. When I had a question about how to handle a specific business expense, they had detailed explanations that actually made sense. Just printed everything out yesterday and mailed it off - saved me at least $500 compared to what my accountant quoted me. Thanks for recommending it!

If you're filing by mail, be prepared for a potentially frustrating experience if you need to follow up with the IRS about anything. I mailed my S-Corp return last year and then had questions about processing, but it was IMPOSSIBLE to get through to anyone at the IRS. Spent literally hours on hold multiple times. I eventually found this service called Claimyr (https://claimyr.com) that actually got me connected to an IRS agent in about 20 minutes instead of the hours of waiting. You can see how it works in their demo video: https://youtu.be/_kiP6q8DX5c It was a lifesaver when I needed to confirm they had received my paper return and check if there were any issues. The peace of mind was worth it because with paper filing, you don't get any confirmation that they received your documents unless you pay extra for certified mail tracking.

I need to eat my words here. After posting my skeptical comment, I got desperate trying to confirm whether the IRS had received my S-Corp extension form that I'd mailed. After my fifth attempt waiting on hold for over an hour and getting disconnected, I reluctantly tried Claimyr. I was connected to an IRS representative in 18 minutes. EIGHTEEN MINUTES. After spending a combined 7+ hours on previous attempts. The agent confirmed my extension was processed and gave me some additional guidance about my filing. I'm still shocked it actually worked. Apparently they use some kind of algorithm to identify the best times to call and have a system that holds your place in line. Whatever they're doing, it works. If you're paper filing and need to follow up on anything with the IRS, it's absolutely worth it.

Just want to add my experience - I've been filing my S-Corp by mail for 3 years now. It's totally fine but make sure you send it CERTIFIED mail with return receipt. It's only a few bucks extra at the post office and gives you proof of mailing/delivery in case the IRS ever claims they didn't receive it (which happened to me once). Also remember to make copies of EVERYTHING before sending. I learned that lesson the hard way when the IRS claimed I never included a required form and I had no way to prove I did. Now I scan everything before mailing.

Has anyone tried the free fillable forms directly from the IRS website for 1120-S? I'm wondering if that's a viable option to save on software costs while still getting the calculation help.

One thing I haven't seen mentioned yet - if you're mailing your 1120-S, make sure you're aware of the March 15th deadline (or September 15th if you filed an extension). The IRS considers it timely filed if it's postmarked by the deadline, not when they receive it. This is different from some other tax situations where actual receipt date matters. Also, double-check that you're using the most current forms for tax year 2024. The IRS sometimes makes small changes to forms between years, and using an outdated version can cause processing delays. You can download the latest versions directly from irs.gov to make sure you have the right ones. One last tip - if your S-Corp had any unusual transactions during the year (like asset purchases, loans, or changes in ownership), you might want to consider at least getting a consultation with a tax professional even if you prepare the return yourself. The basic 1120-S isn't too complicated for simple situations, but certain transactions can have tricky reporting requirements that aren't obvious.