curl -X POST https://api.chargeapi.co/v1/invoices/inv_AAYkYIM6c3Q4daTuAizl4U6SoAcOO2aL \
  -H "Authorization: Bearer ch_sk_test_..." \
  --json '{
  "description": "Updated invoice memo for the March 2026 billing period."
}'

{
    "id": "inv_AAYkYIM6c3Q4daTuAizl4U6SoAcOO2aL",
    "object": "invoice",
    "amount_due": 2500,
    "amount_paid": null,
    "created": "2026-05-02T00:26:05.345Z",
    "currency": "eur",
    "description": "Updated invoice memo for the March 2026 billing period.",
    "due_date": "2026-05-09T00:25:49.394Z",
    "fleet": "flt_ZvhAb1gYDNx6AnM9BowgxXg1bisZoTNh",
    "line_items": [
        {
            "amount": 1842,
            "description": "Charging sessions for March 2026",
            "quantity": 1,
            "unit_amount": 1842
        },
        {
            "amount": 658,
            "description": "Reservation fees",
            "quantity": 2,
            "unit_amount": 329
        }
    ],
    "metadata": {},
    "paid_at": null,
    "payment_method": null,
    "period_end": "2026-05-02T00:26:13.544Z",
    "period_start": "2026-04-01T00:26:03.228Z",
    "status": "draft"
}