Sage VAT amendable button

sheelagh

The Sage guidance issued today includes advice to click the VAT Amendable button in VAT Settings. They say this allows you to manaully amend the VATwhen entering a supplier invoice.
Well, can't you do this anyway? I thought, in fact I know, that you can change the VAT amount in the batch customer and supplier windows.
So, what am I missing? When would this check box be useful?

PGM

I think its more to do with output vat than input?

I had to tick this box to do a vat only invoice a while back.