# BT-73 — Invoicing period start date

> https://billhorse.com/en/terms/bt-73/

First day of the period the invoice covers — relevant for recurring services like maintenance or rent.

## Where does it live in the XML?

- UBL: `cac:InvoicePeriod/cbc:StartDate`
- CII: `rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeSettlement/ram:BillingSpecifiedPeriod/ram:StartDateTime/udt:DateTimeString`