A business with four partners splits up with one partner going on his own and the remaining three staying with the original entity. On the day of the split there is an accounts receivable of $40,000. Historically 50% of gross goes to expenses such as salaried employees and rent. There are no expenses associated with the collection of the A/R. If this is treated “as if” the business closed its doors and the partners went their separate ways then each partner is entitled to $10,000. Or should the solo partner receive $5,000 i.e. less 50%?

Wouldn't a better way be to prepare up to date financial statements upon the date he is leaving?

If of that $40,000, $20,000 (50%) must go to expense incurred BEFORE he leaves, then yes he only gets $5,000. If its for future activities, he is entitled to $10,000