@BigRedConsulting 

"If correct, if you want the down payment to be treated as a deposit, then you can record it the way Intuit recommends lawyers do, as a retainer invoice and related payment (which will create two invoices for each sale). To record such an invoice, create and use a non-taxable item that uses a liability account as the 'income' account. Then use the item on a retainer/down payment invoice, and then receive the payment against it, which will pay it off.

Then, when recording the actual sale, in addition to the other things on that sale, use that new item again but this time with a negative amount, which will reduce the invoice total by the retainer/down payment amount."

I'm not trying to take anything away from your very good post, but I think it's worth mentioning that the issue with that (and I wish QB would mention this) is that QB cannot calculate accurate cash basis income when using that method.  Also, for whatever reason, QB doesn't calculate the Gross Total on the sales tax liability report correctly with that method.  Another thing QB should mention.