The Invoice That Carries a Prior Balance
A guest from Ireland books two weeks at a Gulf Coast property. They paid a deposit at booking. They owe the balance thirty days before arrival. They also have a small unpaid amount from a late checkout fee on their previous stay two years ago. This invoice needs to show the current rental amount, the applicable state transient occupancy tax, the prior unpaid balance, minus the deposit already received, to arrive at the actual amount due.
A single-field invoice amount does not solve this problem. A calculated Total Payable field that adds invoice amount, tax, and previous amounts owed, then subtracts amount paid, does.
Invoice Type as a Legal Classification
Tax Invoice, Invoice (Non-taxable), and Credit Note (Credit Invoice) are not stylistic choices — they are legally meaningful document classifications in US short-term rental markets. A standard rental invoice is a Tax Invoice when the transaction is subject to state sales tax and local transient occupancy tax, which it is in Florida, California, Texas, and most major rental markets.
A Credit Note applies when a booking cancellation results in a partial refund that exceeds the current invoice amount. Rather than issuing a negative invoice, which creates accounting problems, a credit note documents the refund obligation as a separate document type. Having the Credit Note option in the same template as the Tax Invoice means the entire transaction history for a guest — booking invoice, balance invoice, any credit note — is in the same database, searchable by guest name or invoice number.
Non-taxable invoices apply to service components that are not subject to transient occupancy tax under specific state exemptions — monthly stays in some jurisdictions, for example, or specific cleaning or concierge services. The classification matters for remittance reporting to state revenue departments.
Total Payable as the Arithmetic That Doesn't Lie
The Total Payable calculation — #{invoice amount}+#{tax amount}+#{previous amounts owed}-#{amount paid} — is straightforward but its component structure is where the work is. Previous Amounts Owed requires the operator to look up what the guest owes from prior interactions before issuing the invoice. Amount Paid is entered with a negative sign convention per the field hint, which means the calculated field works correctly as long as the data entry discipline holds.
The International guest billing context — the Country field spans Australia, Austria, America, Bolivia, Asia/Pacific, England, Ireland, Middle East, and Other — tells you this is a luxury rental operation whose guests arrive from multiple countries, whose booking currency is USD regardless of origin, and whose invoice addresses span an unusual geographic range for a Florida short-term rental. State and Post/Zip Code fields handle US domestic addresses; for international guests, State captures the overseas region and Post/Zip Code captures the international postcode.
Due Date as a separate field from Invoice Date allows for flexible payment terms — 30-day net for some guest relationships, due immediately for others, due on the final confirmation payment date for bookings. The invoice date stamps the document issuance. The due date determines when the balance becomes overdue.
The Service/Product free-text field captures what the invoice covers: rental period, cleaning fee, pet fee, pool heating, airport transfer — the line items that the invoice amount represents, without requiring a multi-line invoice structure that a mobile database record cannot easily display.