The simplest way to form a selection of suppliers to confirm balances with is to confirm them all. It’s timeconsuming most probably due to the amount of confirmations you would have to perform, however there’s no thought process involved as to which to confirm and which to leave unconfirmed. There’s no doubt either whether those left unconfirmed are in fact existing and so on. 

However, if you’ve decided that there’s a certain limit you consider acceptable to not confirm, i.e. balances not exceeding a determined amount or zero balances for instance, just ensure that you’ve considered the limit for yourself. There’s no rule as to say 90% of the total balance must get confirmed. There’s just you and your own comfort you’re seeking from the process.

A question that often arises is whether to confirm those balances which are zero. How I always respond is this, if there have been considerable transactions with the supplier during the period, confirm. If there haven’t been any transactions with the supplier than it would look rather silly to send a confirmation letter to them to confirm that you don’t owe them. Of course situations may vary and in case in doubt, there’s no fault within sending the confirmation letter out regardless of the volumes.