---
title: "Is this patent alive? Maintenance fees and expiration"
method: GET
path: "/v1/patents/{patent_number}/maintenance"
tags: ["patent status"]
---

# Is this patent alive? Maintenance fees and expiration

`GET /v1/patents/{patent_number}/maintenance`

## Request

- Base URL: `https://api.patentdata.ai`
- URL: `https://api.patentdata.ai/v1/patents/{patent_number}/maintenance`
- Auth: one of:
  - API key in header `X-API-KEY`
  - HTTP bearer

Answers: is this patent still in force, have its 3.5/7.5/11.5-year maintenance fees been paid, and when does it expire. Returns `events` (every fee event: paid, reminder, expired, reinstated), `windows` {"3.5y", "7.5y", "11.5y": paid|due|expired|n/a}, `expired` (true once a fee lapsed or the term ended), `expiration_reason`, and `expiration_estimate` (`term_start` + 20 years + PTA, where `term_start` is the earliest filing date the patent claims benefit from under 35 U.S.C. 120/121/365(c), else its own filing date; `estimate: true` because terminal disclaimers may shorten it). Window values: paid, due (payable now), grace (overdue, surcharge), expired, upcoming (not yet payable), n/a (design/plant/reissue owe no fees); `deadlines` carries each window's opens/due/surcharge_until dates and `next_fee` the first unpaid window (null when the patent is not alive).

## Path parameters

- `patent_number` string, required: US patent number without commas; design/plant/reissue prefixes allowed (D912345, PP12345, RE48123).

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/patentdata/apis/patent-status-api.md) · [All operations](https://skmtc.dev/patentdata/apis/patent-status-api/llms.txt) · [OpenAPI document](https://skmtc.dev/patentdata/apis/patent-status-api/revisions/320133a82b42?raw)