How Murblz builds its open data

Every figure in our datasets comes from a law or an official government source, and every row shows the date it was checked.

Version 2026-10-07 · Next review by 2027-02-07 · CC BY 4.0

This page covers the three Murblz datasets: second passport cost, the program changes log and relocation taxes, which covers 145 countries. The Passport Index and Residence Index have their own method, set out on their pages.

Sources

We use laws and the official websites of ministries, migration and tax authorities and citizenship programs. Media, rankings and private guides are not used.

Each row gives the source it was checked against and the check date. 13 countries in the tax dataset (rules taken from OECD summaries or the text of the act) and 2 programs have no official online source yet: their source cell in the CSV is empty, and these countries are left out of the tax rankings.

Currency and rounding

Amounts are in US dollars. Second passport cost and relocation taxes use the official rates of 2 October 2026: the European Central Bank for the euro ($1.1225 per euro), the National Bank of Poland for the zloty and other central banks for their currencies. The program changes log uses the European Central Bank rates of 5 October 2026 ($1.1204 per euro).

Converted amounts are rounded up: program costs to the next $5, amounts in the tax rankings to the next $100.

Review cycle

A row is updated as soon as a law or an amount changes, and every row is re-checked at least once every 4 months. The next full review is due by 2027-02-07.

Versions

The datasets were first published on murblz.com on 5 October 2026. Each new version enters the version history with its date and what changed.

Corrections

Found an error or a newer official figure? Write to hello@murblz.com with the dataset, the row and a link to the official source. Every report is checked against the source, and each fix goes into the next version with its date.