---
search:
  tags:
    - billing
    - POST
seo:
  description: >-
    Marks the first reminder for an invoice as… Reference for the POST
    /billing/invoices/{id}/mark-first-reminder-as-sent endpoint in the Leadtime
    Public API API.
sidebar:
  badge: POST
  label: Mark first reminder as sent
title: Mark first reminder as sent
type: openapi-operation
---
Marks the first reminder for an invoice as sent to the customer. This records the first reminder date and contact information.

**What happens when you mark a first reminder as sent:**
1. First reminder date (`firstReminderAt`) is recorded as the current date
2. First reminder type is set to "Manual" (indicating manual marking, not email sending)
3. Contact recipient is recorded (from invoice contactId)
4. User who marked it as sent is recorded

**Important restrictions:**
- Only invoices with status "New" or "Sent" can have reminders marked as sent
- The invoice must be overdue (past its due date) to send reminders
- This endpoint marks the reminder as sent manually (use send reminder endpoint for email sending)

**Use cases:**
- Record that a first reminder was sent manually (e.g., via postal mail or other channels)
- Update reminder status after external sending
- Track reminder history

**What is returned:**
- Success response confirming the first reminder was marked as sent

<Operation source="api-reference" id="invoicescontroller-markfirstreminderassent" />