All about Japan’s Koseki: the family register system

Japan’s family register or koseki system is a civil registration system that records details such as births, deaths, marriages and family ties.

Many countries register citizens individually, but in Japan instead of the individual, the family unit is registered. If you ever engage our team there’s a big chance that we will need to gather copies of the koseki to proceed with inheritance or will creation.

What exactly is a copy of the koseki? And how does the system actually work?


The history of the koseki system

The koseki family register system was introduced in 1871 upon the end of the Edo Period. Many features from the 19th century, such as indexing the household by location (honseki or “legal domicile”), and the format that centers around the head of the family still remain today.

Because records go back so far, family ties and subsequently the heirs of deceased persons can be traced from 1871 onward.


How does the koseki system work?

For a Japanese national whose parents were married when they were born, they will become an entry into their parents’ koseki. For children born outside of marriage, either the mother will form a new koseki, or if she was alone in a koseki, the child will be added to hers. For a child to be noted on their father’s koseki or for the father’s details to be recorded in an entry in the mother’s register, the father would have to go through the procedure of acknowledging paternity.

After that, whenever there is a case of adoption, marriage, divorce, or death, records of this are reflected on the koseki. It is also possible to remove oneself from one koseki and start another. You can also voluntarily leave a koseki and create a new one at a new legal domicile.

Such changes should be reported by the individual themselves to be reflected in the koseki, because the government does not change it automatically.


Marrying a Japanese national or having a Japanese child

Only Japanese nationals can be listed on the koseki. If you are a foreigner marrying a Japanese national, the Japanese national will start a new koseki and the marriage will be noted on there, but you will not be added because you’re not a Japanese national. If you have children, they will be added under the Japanese’s national’s koseki.

A foreigner married to a Japanese national will have their name, date of birth and nationality listed on the koseki, but cannot have their own entry.


The koseki and inheriting assets in Japan

Because the koseki serves as an official record of family relationships, it is used to determine heirs and prove connections between individuals.

A certified copy of a koseki is required for procedures such as real estate registrations, closing or changing the name of bank accounts, declaring inheritance tax, and renouncing inheritance.

Koseki records can also be used to prove the connection between the testator and Japanese beneficiaries in a will.


Obtaining a certified copy of a koseki

Although you cannot access the original record, you can apply to obtain a certified copy of the koseki at the local government office where the koseki resides.

There are several types of koseki copies that can be requested, which show different levels of information. For instance, if you’re a foreign spouse of a Japanese national, you can apply for a copy of your partner’s koseki.

We are often called upon for help regarding obtaining relatives’ koseki in order to solve inheritance cases, which sometimes evolves into the need to reach out to municipal governments across Japan.

If you need help regarding obtaining koseki or otherwise proving family relationships to settle inheritance matters, contact us today to schedule a free consultation.

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