For a sample of trade receivables try to trace them to cash book if they cant be found it can assured tht they r nt yet paid and r rightly included in receivable?
Can this be regarded as a substantive proc carried out for existence assertion?
If they are not in the cash book before year end then, provided they were valid receivables in the first place, they would be outstanding at year end.
But be careful, someone not paying you something is not of itself proof that they owe you anything and the legitimacy of the receivable has to be established.