Kiosk: receipt, invoice and the carryover

Every line bought in the kiosk produces exactly one tax document, never two and never none. Which one it is depends on whether the member pays immediately.

| Route | Document | |---|---| | The member pays the open kiosk tab | a receipt for the payment, own number range | | The member does not pay | a position on the monthly kiosk invoice |

What hangs on that:

• The receipt is a small-amount invoice under § 33 UStDV. It carries the provider, the date, quantity and kind, the gross amount and the VAT per rate. It carries no sequential invoice number and no recipient details, and it does not touch the invoice number range. It still entitles the holder to deduct input tax. See Receipt and invoice.
• Below €0.50 no kiosk invoice is produced. The payment provider's minimum is 50 cents. The open lines are not discarded but carried into the next run, until the sum is enough. The same limit also disables the pay button on the tab.
• The month-end run has no lower time bound. Everything that hangs on no document yet comes with the next run. See The first kiosk invoice is unusually large.
• Positions are aggregated, per product name, price and tax rate. A month of daily coffee is one line with a quantity. If you reprice mid-month, the two halves stay separate because they really were bought at different prices.
• The tax rate belongs to the position, not to the invoice. One kiosk invoice can carry several rates; VAT is rounded once per rate, and the PDF prints one line per rate.
• Kiosk is always collected, even from a member who transfers their rent. The purchase was tied to a stored payment method the moment it was tapped.
• An abandoned purchase only counts as abandoned when the payment provider confirms it. If a wallet payment confirms a second later after all, it counts and the receipt attaches to it. A truly cancelled payment falls away and the lines drop back into the tab.
• Cancelling works until the purchase hangs on an invoice. Afterwards a partial refund with a correction receipt remains. If you refund only part, only the amount is recorded; the state flips to refunded only on a full refund.
• The member themselves can undo a purchase for 60 seconds. As soon as they start paying, that window closes.