Deposit Won't Save wo Bank Account, but it is already there...

I've got your back to get past the error message and categorize your deposit successfully, @k12business. 

The Undeposited Funds account in QuickBooks Online serves a special function – it’s a special temporary account that QuickBooks uses to hold payments received from invoices before you deposit them into the bank. It's not an actual bank account which is why there's an error when saving it.

Otherwise, we can perform some troubleshooting steps to fix this. There are times that the browser is full of frequently accessed page resources, which causes some errors or unusual responses. Let's start accessing your account using a different or a private browser. You can use either of these shortcut keys:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Shift + N

Once you have successfully added a hire date, go back to your regular browser and clear its cache. This is done to speed up the process next time you do a transaction in QuickBooks Online. Also, an alternative way is to use other compatible browsers.

Once done, continue categorizing the deposit. For more information about the process, please check out this article: Categorize and match online bank transactions in QuickBooks Online.

Fill me in if you have other questions about categorizing and managing your deposit in QuickBooks. I'll be around to help you. Stay safe!