Generate random valid-format My Number (個人番号) numbers for testing
Paste a My Number (個人番号) below to check whether it has a valid format and correct checksum.
My Number (マイナンバー, officially 個人番号 — kojin bangō) is a 12-digit social security and tax identification number assigned to every resident of Japan, including foreign nationals with medium- or long-term residence status. Introduced in 2016 under the Act on the Use of Numbers to Identify a Specific Individual in Administrative Procedures, it is used across the pension system (nenkin), health insurance, employment insurance, tax filing, and disaster relief applications.
Unlike China's Resident ID or France's INSEE number, My Number contains no embedded personal information such as birth date or region — it is a randomly assigned number in the range 000000000001 to 999999999999, excluding those with invalid check digits. Numbers are typically displayed in groups of four digits (XXXX XXXX XXXX). The 12th digit is a check digit that provides structural integrity without encoding any demographic data about the holder.
The check digit is calculated using a weighted modulo-11 algorithm: the 11 base digits are multiplied by the weights [6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2], the products are summed, and the sum is taken modulo 11. If the remainder is 0 or 1, the check digit is 0; otherwise, the check digit is 11 minus the remainder. This algorithm is identical to the one used for Japanese corporate numbers (法人番号), establishing a consistent verification standard across Japan's digital identity infrastructure.
Social security software, tax filing systems (e-Tax / eTax), HR platforms, and government service portals in Japan all require valid My Number handling. The My Number Card (マイナンバーカード) also stores the number on a contactless IC chip, meaning applications that read NFC cards need correctly formatted numbers for device testing. Generating structurally valid fake My Numbers allows developers to test field validation, IC chip parsing simulations, and J-LIS (Japan Agency for Local Authority Information Systems) API integrations safely.
Japan's Digital Agency (デジタル庁) has been aggressively expanding My Number Card usage since 2021, linking it to health insurance cards, driver's licenses, and the Myna Portal digital government platform. As of 2024, over 70% of Japan's population has obtained a My Number Card. Applications integrating with Myna Portal APIs, the Social Security and Tax Number system, or Japan's health insurance card replacement program need valid fake My Numbers to test authentication flows, consent management, and data linkage features in staging environments.