A parent asks for a receipt — do I have to make one by hand?

No. An invoice that is fully paid can be downloaded by the parent as a PDF receipt from the Parents Portal, complete with the invoice number, its line items, and the school's identity.

Receipts are only issued for invoices that are genuinely settled. An invoice that is partly paid cannot be downloaded as one, because a document saying PAID over an unpaid balance is a document that lies.