I'm getting below error when i try to use IGST. 400 Bad Request: [{"Fault":{"Error":[{,"code":"6000","element":""}],"type":"ValidationFault"},"}]

We can perform some troubleshooting steps to get this sorted out, accounts226. 

There are times when a browser's cache data becomes full of frequent access to web pages or damaged. This causes an error when using the IGST in QuickBooks Online (QBO). To better isolate this one, let's try performing some steps below to confirm browser-related issues. Here's how: 

1. Try signing in to your QBO using a private or incognito window. (Ctrl + Shift + N for Google Chrome browser, Ctrl + Shift + P for Mozilla Firefox browser, Command + Option + P for Safari browser). 
2. If it works, go back to your regular browser and clear the cache to delete those temporarily stored files and browsing history. The overtime collection of data can create corruption, however, removing this should fix the issue.
3. You can also use supported, up-to-date browsers to roll out the possibility of a browser-related issue. 

If the same thing happens, I'd suggest contacting our Customer Support Team. They'll pull up your account in a secure environment and investigate what's causing this issue. Here's how:

1. Go to the Help menu at the upper right.
2. Select Contact Us.
3. Enter your concern.
4. Click Let’s talk.
5. Choose Start a chat. and type in your contact info.

Visit our Tax page to learn more about managing your VAT on your business. 

I'd like to know how you get on after performing the steps or after reaching out to our support, as I want to ensure this is resolved for you. Just reply to this post and I'll get back to you. Take care always.