Once you have uploaded your bank transactions in QuickBooks Online (QBO), the transactions will post in the For Review tab on the Banking page for you to add, match, and categorize since those data are not yet in your register.
To split a bank transaction, here's what you'll need to do:
In the left menu, click Transactions or Banking.
Tap the Banking tab and go to the For Review section.
Locate and click the transaction you want to split.
Select the Split button.
For each part of the split, enter the necessary information.