A payment confirms that money arrived. It does not confirm that the entire amount belongs to the business as profit. Some of it may need to cover the stock sold, operating costs or other obligations.
Match each payment to the sale or invoice it settles. Check the date, reference and amount, and investigate duplicate entries, refunds and payments with no clear match. Keep transfers between your own accounts separate from customer revenue.
Reconcile your payment records regularly rather than relying on an account balance. A clear record of sales, costs and collections helps you understand what has been earned, what is still owed and what cash is available.