Thank you for your interest in our product, @andr1s.
Yes, it's necessary to bring your old transactions to QuickBooks for audit purposes. I'd like to provide a few details about this and help you from there.
I understand that you would like to start fresh with QuickBooks so your data won't screw up. However, your Tax/GST/VAT agency will make an audit for all of your transactions.
If you would like to transfer your transactions, I suggest importing them in QuickBooks. For your reference, you can check out this article for more information: Common Questions about Importing Data to QuickBooks Online.
Also, with regards to the records that don't match to your old software, I recommend seeking help from your accountant. He/she could guide you on how to properly record those transactions in QuickBooks.
You might also want to read these articles to get started with QuickBooks:
Feel free to leave a reply below if you have further questions with QuickBooks. The Community team and I are always here to help.
