Its my first tax year as a sole trader so I am trying to get my head around all of this. 
Payments to Royal Mail and Parcelforce for customs and VAT puzzles me. I can lump it and tag as a simple cost invoice with 20% VAT, but is that accurate?
And is the entire bill reclaimable to HMRC, as it is customs duties, VAT, service charge, and VAT on the service charge?
Are you vat registered? if not you cannot reclaim vat. It will be part of total expense
Yes I am VAT registered.
Only vat element is reclaimable subject to proper documentation as backup, any other taxes i.e excise or charges are part of cost
Ok, yes, that is what I had understood. However, my confusion is with tagging, and how to record the payments to the carrier correctly. There is a handling fee, VAT payment, and sometimes customs charge.
You need to book the invoice first then tag payment to invoice
Good, I’m on the right track! Do I bother creating separate lines for the different fees?
Most importantly, what is the best tag for VAT payments made to Royal Mail?
I’m having the same problem. Often Import Vat and other fees aren’t an exact )or correct) percentage of the cost of a stock item. Therefore the amount charged needs to be reclaimed as a separate figure : it can;t be determined correctly by just deducting 20%
The trick to doing this sort of thing in QuickFile is to record a purchase with two lines for the import VAT - work out what “net” that VAT amount would be 20% of (i.e. VAT times 5), then put one line for that amount at 20% VAT and another line for minus the same net at “no VAT”. This leaves just the VAT.
Then you could record the import duty and fees as further lines, at the appropriate VAT rate as per a normal purchase.