Payments in, invoices out.
The books should balance on their own.

1. 1
   A payment arrives

   Read from the bank feed as it lands.

2. 2
   Compared

   Amount, reference and customer against open invoices.

3. 3
   Matched

   The right invoice is found, even with a typo in the reference.

4. 4
   Marked paid

   Receipt sent, books updated, the scale is level.

5. 5
   No match? A person checks

   Nothing is guessed or forced.

Amounts and references are examples. Partial and grouped payments are handled with the same rules.