I added v-bucks to my microsoft account instead of my son's. Can I transfer?

Unfortunately, V-Bucks can not be transferred from one account to another.

What I would suggest is requesting a refund, information on how to do so can be found here:

https://beta.support.xbox.com/help/subscriptions-billing/manage-subscriptions/digital-goods-subscriptions-refund.

If you still wish to send V-Bucks to your son, I recommend purchasing Microsoft Gift Cards which will give you the ability to gift the code to your son to add to his account. Once added to his account, he can then purchase V-Bucks through his own account
via the Microsoft Store.

I'm sorry you had such a bad experience.

But can you tell us if you were signed in with your own account on your laptop when you purchased the V-Bucks?

Does your son have their own child account? Or are they using your adult parent account (which they should NOT do)? If the kid has their own account, and they were added to your Family through
https://account.microsoft.com/family you can gift them an allowance so they can buy stuff like V-Bucks for themselves.

The problem is, that "consumables" like V-Bucks (unlike "persistent" items like games or game add-ons) cannot be gifted/transferred after purchase. So if you made the V-Bucks purchase with your own account, then the V-Bucks went to your parent account instead
of your kid's account.

Maybe this will help avoid such a confusing purchase experience in the future.

Hi, no V-Bucks are not transferable between accounts. Instead you can spend them on gifts from one account to the other....

Consumables like Fortnite V-Bucks have to be purchased by the account that is supposed to use them.

Unfortunately, there is no way to transfer consumables to a different account. While it is possible to buy a game and some DLCs that your son can play thanks to the Home Console setting that shares your game purchases with the first console you set up with
your account, consumables can't be shared to a console.

Therefore your son can't see the V-Bucks in his account, as the V-Bucks are stored on your account, and not shared to the console.

In order to get your son V-Bucks, you would have to buy him a currency gift card, that your son then redeems, and with which he can then buy V-Bucks for himself.

Seems like the only option is to find someone who needs a game and gift it to them and get them to buy me a new gift card for the same amount to then redeem on my son's account.

Lots of people with the same problem on the forums, also people who have bought V-Bucks on the parent's account and then can't transfer them to the kids account ( glad I saw that before I made the same mistake).

Tried logging into x-box with my account and then logging into fortnite with my sons account to buy the v-bucks with my money but that isn't possible either as the fortnite account is locked to my son's login.

Thanks for your suggestions but looks like I will just have to ask around or wait to see if there is a game I can gift to him or a friend in the future.