One number is assigned by the Ministry of Interior, the other is required under the tax-number law. Here is which number goes on a form, how to obtain the foreigner ID, and when a separate tax number must be obtained before a listed transaction.
Opening a bank account or going to a notary often starts with a form asking for a tax number. But a foreigner who already has a foreigner ID number (YKN) writes that number in the tax number field. According to the official legislation database and the migration authority's page, both checked on 4 November 2026: the YKN replaces the tax number for its holder, a tax number must be obtained before a listed operation is completed if you do not have one, and a foreigner who applies to a Turkish state institution or foreign mission can ask for a YKN. Here is which number goes where, how to get the YKN, and what the law requires at the notary and what banks ask for in practice.
Which number do you write in the tax number field?
The General Communiqué on the Tax Number (series 4) answers this directly: a foreigner who already has a foreigner ID number (YKN) writes that number in the tax number field. The YKN replaces the tax number for that person. In practice this means you do not need to apply for a separate tax number, and you should not treat a form's box labelled 'vergi kimlik numarası' as asking for a second, different number. The number you already hold is the number the form expects.
When a form or a clerk asks for your tax number and you hold a YKN, give the YKN.
How to get a foreigner ID number
Article 8 of Law No. 5490 on demographic services, as amended by Law No. 7148 of 18 October 2018, assigns a foreigner ID number to persons covered by Law No. 6458. A foreigner who applies to a Turkish state institution or a foreign mission for any matter can ask for the number. Diplomats are outside this provision.
Syrians under temporary protection can look up their YKN free of charge on the migration authority's website, using the personal number starting with 98 on their temporary protection card.
When you must obtain a tax number before a transaction
Article 2 of Law No. 4358 on the introduction of the tax number creates the obligation: a participant in an operation from the Ministry of Finance's list must obtain a tax number before the operation is completed if they do not already have one. The trigger is narrow. It applies to operations that appear on that list, not to every transaction a foreigner makes. If your planned operation is on the list and you have no tax number, the law requires you to obtain one before the operation is finished.
The law fixes when the number must exist — before the listed operation is completed — not how to obtain it.
Opening a bank account: what banks actually ask for
Legal and consultancy publications, the latest dated 24 September 2026, report that in practice Turkish banks require a tax number from a foreigner without a residence permit before opening an account. Requirements vary by bank, so one bank's demand is not a universal rule. A foreigner without a residence permit should expect the tax number to be part of the account-opening checks, even though the publications describe this as bank practice rather than a statutory condition.
A financial comparison portal, as of 26 August 2026, and lawyer commentaries add that the law itself does not require a residence permit for opening an account. However, some banks ask for one or slow the process, so you may need to approach several banks. This is field practice, not a legal requirement: the bank's demand can be stricter than the statute, and the solution the sources describe is to try another bank rather than to expect the first one to change its rule.
At the notary: which number to give
Article 101 of the Notary Law requires the notarial protocol to state the interested person's identity, address and tax number. When a notary prepares a document for you, the tax number is one of the items the protocol must record, alongside who you are and where you live. The law does not make this optional: the protocol is expected to contain all three.
For a foreigner who holds a foreigner ID number (YKN), the General Communiqué on the Tax Number (series 4) says the YKN replaces the tax number for that person. So when the notary asks for your tax number, give the YKN you already have. Before the appointment, confirm with the notary office that the YKN is what they enter in that field.
Got a foreigner ID after tax registration? Report it within a month
The General Communiqué on the Tax Number (series 4) addresses a specific situation: a foreign taxpayer who was already registered with the tax office and later received a foreigner ID number (YKN). That person must report the YKN to their tax office within one month of receiving it.
What happens if you conceal the number or give false details
Article 5 of Law No. 4358 attaches a criminal penalty to the tax number. Three acts are covered: concealing a tax number, knowingly providing false information about it, and using false documents.
The penalty is imprisonment for three to ten months. The law sets this range, not a fixed sentence; what a court imposes in a particular case depends on the circumstances.
The provision refers to knowingly giving false information about the tax number. If you have given an incorrect number or details, correct it with the tax office and seek advice from a lawyer or tax adviser.
The practical rule is to use the number you actually hold and to write it as it appears on your document. Concealment and false details are the acts the article penalises.