There are no fees for having a Microsoft account, putting money into it, or using it to buy stuff from us. In other words, it’s free!
Is a Microsoft account free?
A Microsoft account is a free account you use to access many Microsoft devices and services, such as the web-based email service Outlook.com (also known as hotmail.com, msn.com, live.com), Office Online apps, Skype, OneDrive, Xbox Live, Bing, Windows, or the Microsoft Store.
Is it necessary to have a Microsoft account?
What is Microsoft charging me for?
From what I have understood through Microsoft and my bank is that a pre-auth charge is what Microsoft does to ensure that you have the funds in your bank account before the purchase goes through. Once the purchase itself has cleared your bank account the pre-auth charge should return.