How to categorize a downloaded bank transaction into category, transaction type, customer/ supplier and tax?

Hi sparepacnisku-gm,

It's nice to see you in Community.  Welcome!  QuickBooks Online simplifies your work by providing the option to create Bank Rules.  However, for the current issue at hand, it's best to reach out to an accounting professional for the best course of action.  It's important that you're transactions are entered accurately with a positive outcome on all areas of your books.  If you don't have an accountant, we can help you locate a ProAdvisor in your local area.  

Feel free to reach back out with other questions.  We'd be happy to help!