What exactly is the "State ID number" on 1099-B tax forms?

The "State ID number" they're asking for is actually your broker's state identification number, not yours. This is typically the state tax ID number assigned to the brokerage firm - it's how they're identified for state tax purposes. You should be able to find this number on your 1099-B form, usually in a box labeled "Payer's state ID no." or something similar. It might be near where they show the state tax withheld information. Sometimes it's printed in a small font at the top or bottom of the form along with the brokerage's address. If you can't find it anywhere on the form, it's possible your particular brokerage doesn't have state withholding or reporting requirements for your state. In that case, you can leave this field blank and the software should still allow you to continue.

I had this exact same issue last year! I spent hours looking for that "state ID number" on my forms. I ended up using taxr.ai (https://taxr.ai) to scan my tax documents and it immediately identified that I didn't need to enter anything in that field since there was no state withholding. The tool basically analyzes your tax documents and translates all the confusing parts into plain English. It saved me a ton of time because it also explained how to handle some weird wash sales I had. The document analysis feature was super helpful because it told me exactly what information needed to go where in my tax software.

I was skeptical about trying taxr.ai at first because of privacy concerns, but I decided to give it a shot with my complicated 1099-B situation. Wow, what a difference! The tool immediately identified that my broker (Fidelity) had a state ID number hidden in tiny print on page 3 that I completely missed. It also organized all my crypto trades which saved me hours of manual entry. The interface was super straightforward - I just uploaded my documents and it pulled out all the relevant information in seconds. When I had a question about a specific line item, there was a feature to ask about it directly. I'll definitely be using it for all my tax documents next year instead of playing "where's waldo" with important tax information!

If you're still stuck with the 1040.com issue and can't reach their support, you might want to try Claimyr (https://claimyr.com). It helped me get through to actual IRS support when I had a similar problem with state ID numbers on investment forms. They have a service where they can connect you directly to IRS support without the usual 2+ hour wait. There's a video showing how it works here: https://youtu.be/_kiP6q8DX5c - basically they wait on hold with the IRS for you and call you when an agent is about to pick up. I was super skeptical but it actually worked! The IRS agent explained that for most individual investors, if no state tax was withheld, that field can be left blank in most tax software.

I was totally wrong about Claimyr. After spending 3 hours trying to get through to the IRS on my own with no luck, I gave the service a shot. Within 45 minutes, I got a call back and was connected directly to an IRS agent. The agent confirmed exactly what others here said - the State ID number is for the brokerage firm, and if there's no state tax withheld (which was my case too), it's not necessary to enter anything in that field. They also clarified that this varies by state, but for most states, individual investment income reporting follows federal reporting. No one listened in on my call, and I was able to ask several other tax questions that had been bugging me. Definitely worth it when you need actual official clarification on something that Google can't answer clearly.

To answer the original question directly - the State ID number is typically the state tax identification number assigned to your broker by the state tax authority. It's similar to an EIN but for state purposes. If you want to be 100% sure, you could also just call your brokerage directly. I had a similar issue with E*TRADE and when I called them, they gave me their state ID number right away and explained that it's usually only needed if state tax was withheld, which matches what others have said here.

Is anyone else annoyed that tax software asks for stuff that isn't clearly marked on our forms? I've been dealing with this for years and it feels intentional - like they want to confuse us into paying for their deluxe versions or support.

I totally understand your frustration - I had the exact same issue last year with TurboTax asking for a "State ID number" that I couldn't find anywhere on my 1099-B. After reading through all these responses, it sounds like the consensus is that this is your broker's state tax identification number, and if there's no state tax withheld (which shows as $0 on your form), you can usually leave that field blank. What helped me was calling my broker directly - they were able to tell me right away whether they had a state ID number for my state and whether it was needed for my specific situation. Most customer service reps at brokerages are familiar with this question since it comes up during tax season. The good news is that even if you accidentally leave it blank when it should be filled in, or vice versa, it's not likely to cause major issues with your return. The IRS is mainly concerned with the actual income amounts and any withholding, not so much the administrative ID numbers.