Are you talking about bartering? That I don't know. We have used 58 to discount services for work done but the patient won't be charged, as a professional courtesy. We have added extensions to identify if they are doctor and family, employees, pro bono bases etc., meaning those codes would be 58.1, 58.2, etc.
Yes bartering. I just need a code that does not affect the production amounts. We have a bonus system and with code 51 it affects the production amount.
You are correct 21-29 will decrease the patient's balance without affecting production, but please keep in mind it does increase collection. You can create a code in this range if this works for you.
Or, simply post the transaction, with a zero amount. If you would like to keep track of barter amounts you could add the amount in the notes column. Of course, if you need the totals calculated it would take a bit of investigation, the tradeoff is that no totals would be effected.