Overview

Update a draft bill. Only bills in Draft status can be updated. When line items are provided, they replace all existing line items entirely.

Example: Correct a line item amount on a draft bill before finalizing it.

Constraints

• Only draft bills can be updated — finalized and paid bills return 400
• period_start and period_end are required
• When line_items are provided, all existing line items are replaced
• Subtotal and total are recalculated from line items