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Deleting a recurring transaction in QuickBooks Online will not affect previous months' transactions that had this particular transaction. When you delete a recurring transaction, it only removes the future instances of that transaction without altering any historical data.
However deleting a recurring transaction that has already been recorded for the current month, will also delete the associated regular transaction. Always consider the impact of deleting a recurring transaction on your finances before proceeding. Seek advice from a certified accountant if you have any concerns or doubts.
You can use this article to learn more about Review your recurring transactions in QuickBooks Online.
For additional reference, you can click this article on how to Categorize online bank transactions in QuickBooks Online.
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