You might need to complete this form and send it to fedex If you going to use fedex Your SS number going to be your "importer number" on the Bitmain site under address.
If you are using your company tax ID , then use the same number as a "importer number"
Fedex might going to hold ur miners till this form is completed and sent to them , after u paid the custom fees or asked them to send you the invoice they going to release the miners .
Usually for 2-5 miners the fee is around 25$. When you first paying the custom fees via phone , you can ask them to place your card/bank information on file , and set automatic payments for future custom duty fees .
I had trouble with DHL before, never tried UPS , always used Fedex