Currently GST doesn't calculate in Journal entry and in Invoice whereas a week ago it was calculate perfectly
Great job catching that the sales tax isn't calculating correctly early on as coming across these things early helps prevent the need to correct these issues on a larger scale. Having the proper calculations is important not only for your books, but for your remittances, so I want to make sure you get this sorted out.
The first place to start is with clearing your browser or app's cache, trying a different browser, and making sure you're using a supported browser and system. Being a cloud software, QuickBooks Online's performance is largely based on the Internet connection and the way you access the program, which is why these are useful things to try. Check out the How do I clear my cache and temporary Internet files? article to start with cache troubleshooting, then click on the link in that article to learn more about supported browsers and systems. If that doesn't solve it, here's the next thing to consider.
Recently, we've noticed these kinds of issues for customers that migrated their data from QuickBooks Desktop to QuickBooks Online and are still using the QuickBooks Desktop sales tax codes. These are the single letter codes that you'd see in your account; QuickBooks Online's codes are three letters long. To resolve this, make the QuickBooks Desktop codes inactive and then configure QuickBooks Online's built-in codes. Here's how.
Go to Taxes in the left menu.
On the Sales Tax page, click Manage sales tax.
Click Make inactive on the QuickBooks Desktop codes.
To go through those steps with an agent or for further troubleshooting, contact the QuickBooks Online support team. There are a few ways to reach us outside of community, so pick from the options below to connect with an agent who can help you further.
Phone and Chat: ClickContact Us to learn how to reach phone and chat support.
Schedule a Callback: click (?)Help in the upper right > click Contact Us > explain your situation > click Let's Talk > choose Get a callback (Note: Callback hours are the same as regular phone hours.)