Example — replace these figures with your own. An invoice is raised for ₹1,18,000 inclusive of GST. Three payments are recorded against that invoice: ₹40,000, then ₹50,000, then ₹10,000. The outstanding balance derived from those records is ₹18,000, and the ageing reads the invoice by the date it was raised rather than by the date of the most recent payment. Nothing was rounded, adjusted, or written off, so the ₹18,000 is a balance with a complete history behind it — and the conversation with the client can start with the actual position instead of a reconstruction of it.
The same reasoning works in the other direction. If a payment is recorded against the wrong invoice, the fix is a correction on a record with an audit entry, not an edit to a total that quietly absorbs the difference. That is the practical difference between an outstanding list and a bank statement with notes.
If you want to see the arithmetic on your own numbers before you commit to anything, the receivables ageing calculator runs the same buckets against figures you enter, and the payment collection tracker template is the spreadsheet version of the same list for teams still deciding.