minimum_wage_jp 1.2.0

Japan minimum wage by prefecture (日本の地域別最低賃金): rates for any date and compliance checks
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# minimum_wage_jp

> Rust crate for Japan's regional minimum wage (日本の地域別最低賃金) by prefecture.
> Returns the hourly minimum wage in effect on any date and checks whether an hourly
> wage complies. Official MHLW data (2015-2025 revisions) is embedded; per-prefecture
> effective dates are handled with automatic fallback to the previous revision.
> No network access, no API key.

## Install

```toml
[dependencies]
minimum_wage_jp = "1"
```

## API (all associated functions of `MinimumWageJp`)

- `rate(pref: u8) -> Result<u16, MinimumWageJpErr>` — today's minimum wage (yen)
- `rate_on_date(date: chrono::NaiveDate, pref: u8) -> Result<u16, MinimumWageJpErr>` — minimum wage on a date
- `rate_for_revision(year: u16, pref: u8) -> Result<u16, MinimumWageJpErr>` — wage of a revision year (ignores effective dates)
- `is_compliant(pref: u8, hourly_yen: u32) -> Result<MinimumWageJpCompliance, MinimumWageJpErr>` — compliance today
- `is_compliant_on_date(date, pref, hourly_yen) -> Result<MinimumWageJpCompliance, MinimumWageJpErr>` — compliance on a date

Types:
- `MinimumWageJpCompliance`: `Compliant` | `Short { shortage_yen: u32, required_yen: u32 }`
- `MinimumWageJpErr`: `InvalidPrefCode(u8)` | `DatasetNotFoundForDate { date, prev, next }` | `DatasetNotFoundForYear { year }`
- Prefecture codes: JIS X 0401 (1 = Hokkaido/北海道 … 13 = Tokyo/東京都 … 47 = Okinawa/沖縄県)

## Example

```rust
use chrono::NaiveDate;
use minimum_wage_jp::MinimumWageJp;

let date = NaiveDate::from_ymd_opt(2025, 10, 4).unwrap();
assert_eq!(MinimumWageJp::rate_on_date(date, 1).unwrap(), 1075); // Hokkaido
```

## Data

- 2015 revision (Heisei 27): effective 2015-10-01 .. 2015-10-18
- 2016 revision (Heisei 28): effective 2016-10-01 .. 2016-10-20
- 2017 revision (Heisei 29): effective 2017-09-30 .. 2017-10-14 (Osaka came into
  effect on 2017-09-30, the only pre-October date)
- 2018 revision (Heisei 30): effective 2018-10-01 .. 2018-10-06
- 2019 revision (Reiwa 1): effective 2019-10-01 .. 2019-10-06
- 2020 revision (Reiwa 2): effective 2020-10-01 .. 2020-10-09; 7 prefectures
  (Hokkaido, Tokyo, Shizuoka, Kyoto, Osaka, Hiroshima, Yamaguchi) kept their 2019
  rates (recorded as 2020-10-01; values are identical, so lookups stay continuous)
- 2021 revision (Reiwa 3): effective 2021-10-01 .. 2021-10-08
- 2022 revision (Reiwa 4): effective 2022-10-01 .. 2022-10-20
- 2023 revision (Reiwa 5): effective 2023-10-01 .. 2023-10-14
- 2024 revision (Reiwa 6): effective 2024-10-01 .. 2024-11-01 depending on prefecture
- 2025 revision (Reiwa 7): effective 2025-10-01 .. 2026-03-31 depending on prefecture
  (e.g. Tokyo 1,226 yen from 2025-10-03; Akita 1,031 yen from 2026-03-31)
- Dates before the earliest embedded revision return `DatasetNotFoundForDate`
- Source: Ministry of Health, Labour and Welfare (厚生労働省)
  https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/koyou_roudou/roudoukijun/minimumichiran/
  https://saiteichingin.mhlw.go.jp/table/page_list_past.html

## Links

- crates.io: https://crates.io/crates/minimum_wage_jp
- docs.rs: https://docs.rs/minimum_wage_jp
- Repository: https://github.com/uiuifree/rust-minimum-wage-jp