---
title: "Last business day of a month / 月末の最終営業日"
method: GET
path: "/v1/business-days/last-of-month"
---

# Last business day of a month / 月末の最終営業日

`GET /v1/business-days/last-of-month`

## Request

- Base URL: `https://biz.ossalt.jp`
- URL: `https://biz.ossalt.jp/v1/business-days/last-of-month`
- Auth: none declared

Return the last business day of the given month. / その月の最終営業日。

## Query parameters

- `year` integer, required: Year (1980-2099) / 年
- `month` integer, required: Month (1-12) / 月
- `calendar` 'standard' | 'bank': "standard": weekends and national holidays are closed. "bank": also closed Dec 31 - Jan 3 (Japanese bank holidays). / standard：土日・祝日が休み。bank：加えて12月31日〜1月3日が休み（銀行の休業日）
- `extra_holidays` string
- `extra_business_days` string

## Response `200`

OK

- Answer
  - `result` object, required: The answer / 結果
  - `source` object, required: Source and verification / 出典と照合の状況
  - `as_of` string, required: Reference date in Japan time (YYYY-MM-DD) / 基準日（日本時間）
  - `notes` string[], required: Assumptions such as estimated values / 前提（見込みの値など）
  - `flags` string[], required: `flags` holds machine-readable codes: `estimated` (a value is an estimate, e.g. a future equinox day — tell the user), `unverified` (year not yet checked against Cabinet Office data — tell the user), `assumes_current_era` (a future date written in the current era — tell the user), `outside_era` (the era date given is outside that era), `weekday_mismatch`, `closed` (the company's registry record is closed — tell the user), `excluded_from_search`, `truncated`, `not_found`, `exact_match_only`, `partial`, `ambiguous`, `city_not_found`, `ambiguous_city`.

## Other responses

- `400`: Invalid parameters / 入力の誤り
- `429`: Too many requests / 呼び出しが多すぎます
- `503`: Data unavailable / データを読めない

---

[API](https://skmtc.dev/ossalt/apis/japan-business-tools.md) · [All operations](https://skmtc.dev/ossalt/apis/japan-business-tools/llms.txt) · [OpenAPI document](https://skmtc.dev/ossalt/apis/japan-business-tools/revisions/8bb72a25e175?raw)