Hello Rafal_Cube,
It's great to have you with us in the QuickBooks Community. Making sure your balances and transactions are tracking the way you'd like them to in your books is a great way to keep track of what's going on with your business finances. I want to make sure you get the answers you need for writing off your unpaid bills in QuickBooks Online.
Since you're looking for some pretty specific things with this process, I recommend touching base with an accountant. There isn't a built-in method or article that outlines this process for QuickBooks Online, nor is there a report like you're suggesting, so it may take some workarounds and testing to find the right method for you. An accountant, in particular one trained in QuickBooks, is a great resource in these kinds of situations.
There's a help article for QuickBooks Desktop that goes over writing off supplier balances that you can review if you'd like. You'll simply have to keep in mind that the steps are different for completing the tasks it mentions. For instance, the article mentions creating a journal entry, but you'll want to use the steps in Create a journal entry in QuickBooks Online to make that kind of transaction in the version of the program you're using. Here's the article I was mentioning: Write off customer and supplier balances in QuickBooks Desktop
To connect with an accountant via QuickBooks Online, check out the My Accountant tab in the program. There, you can invite someone you're already working with if you'd like them to be a user on your account, or you can use the Find a pro to help button to get access to our database of QuickBooks-certified accountants.
Feel free to also share your feedback about what you'd like to see as features in the program. This helps us as we continue to grow QuickBooks Online to meet the needs of business owners: How do I submit feedback?
Wishing you the best. :)
