Home RNOKPP (РНОКПП) Ukraine
Ukraine RNOKPP (РНОКПП) validator
How the RNOKPP (РНОКПП) format works
- Format
- 10 digits
- Example
- 1759013776
Things to watch for
- 10 digits validated with a weighted mod-11-then-mod-10 check on the final digit
- The first 5 digits encode a serial number derived from date of birth, and the 9th digit's parity encodes sex — we validate format and checksum only, never the date, and never store what you enter
- Checksum only — a valid RNOKPP does not confirm the number is currently issued to a real person
^[0-9]{10}$RNOKPP — реєстраційний номер облікової картки платника податків, Ukraine’s taxpayer registration number — is the 10-digit identifier the State Tax Service issues to residents for tax filings, employment, banking, and most government-facing paperwork. Many Ukrainians still know it by its older name, ІПН, from before the official terminology changed.
Structurally, it stands apart from the other national IDs on this site in how it encodes a birth date. Rather than writing YYMMDD directly into the digits the way an Estonian isikukood or a Czech rodné číslo does, the first five digits of an RNOKPP are a serial number counted as days elapsed since a fixed reference point around 1900 — a birth date is in there, but recovering it means converting a day count, not just reading digits off the page. The ninth digit’s parity marks sex, and the tenth digit is a check digit computed from a weighted sum over the first nine — a sum with one unusual feature: the very first digit carries a negative weight, subtracted rather than added, before the mod-11-then-mod-10 reduction that produces the final check value.
How this validator works
This tool confirms the input is 10 digits, then reruns that weighted sum — including the negative weight on the first digit — through the same mod-11-then-mod-10 reduction used to generate the real check digit, entirely in your browser. Nothing you enter is sent to a server or stored.
What a pass doesn’t tell you
A matching check digit confirms the 10 digits are arithmetically consistent, not that the RNOKPP was ever issued by the State Tax Service or belongs to a real person. This tool never decodes the day-count birth date or sex the digits encode.
Scope: this page covers RNOKPP format and checksum validation only — not identity or registration lookups.
Content last reviewed 2026-08-09.
RNOKPP (РНОКПП) FAQ
What do the 10 digits of a Ukrainian RNOKPP encode?
The first five digits are a serial number derived from the number of days elapsed since a fixed reference point around 1900, rather than a direct YYMMDD date the way most of the other national IDs on this site encode a birth date. The ninth digit's parity (odd or even) encodes sex, and the tenth digit is a check digit.
Why does the RNOKPP checksum include a negative weight?
The weighted mod-11 sum used to compute the check digit assigns a weight of -1 to the very first digit, subtracting it from the running total rather than adding it — an unusual detail not present in most other weighted check-digit schemes on this site.
Is RNOKPP the same as the older ІПН?
Effectively yes — RNOKPP (реєстраційний номер облікової картки платника податків) is the current official name for what was long called the ІПН, or taxpayer identification number, and many people in Ukraine still refer to it by that older name.