Before you start

Ward registration completed
Residence card
Employment details, if enrolling through an employer scheme
My Number

Step-by-step

1
Establish which scheme you are in
Full-time employees are usually enrolled in shakai hoken by their employer, which splits contributions and includes pension. Everyone else — freelancers, part-timers, students, people between jobs — must enrol in National Health Insurance at their ward office themselves. There is no third option of being uninsured.
Via employerWho: YouWeek 1–2
2
Enrol at your Yokohama ward office if your employer does not
Do it in the same visit as your address registration. National Health Insurance is administered by the municipality, so this is Yokohama's scheme with Yokohama's premium calculation — not Tokyo's, whatever your commute suggests.
In personWho: YouWithin 14 days
3
Understand the 30% co-payment and the monthly ceiling
You pay 30% of most treatment costs at the counter. Above a monthly threshold that scales with income, the high-cost medical expense benefit caps what you pay. Apply for a limit certificate in advance if you know a major treatment is coming.
In personWho: You
4
Register with a clinic near home rather than near work
In a commuter city this matters more than it sounds. Japanese clinics rarely take appointments and work on morning and evening walk-in blocks, and a clinic near your Tokyo office is closed by the time you get back. Find a local one before you need it.
In personWho: You
5
Enrol in the pension and keep the records
Pension enrolment is compulsory alongside health insurance. Keep your pension book and every record of contributions — they are what you need to claim the lump-sum withdrawal if you leave Japan.
In personWho: You
6
Claim the pension lump-sum withdrawal when you leave
If you leave Japan having contributed for at least six months, you can claim a lump-sum refund of part of your pension contributions, applied for within two years of departure. It is a substantial sum for anyone who stayed a few years and it is very commonly forgotten.
OnlineWho: YouWithin 2 years of leaving Japan

Documents you’ll need

Residence card
My Number
Health insurance card or registered My Number card
Pension handbook
Jūminhyō residence certificate

Things most newcomers don’t know

The high-cost medical expense benefit is what makes the 30% co-payment survivable.

Paying 30% of everything sounds alarming until you learn that monthly out-of-pocket costs are capped at a threshold scaling with income. A major operation or a long hospital stay costs a manageable amount rather than a catastrophic one. If you know a significant treatment is coming, applying for the limit certificate in advance means the cap is applied at the counter rather than reclaimed later.

Source: Ministry of Health, Labour and Welfare

Most Japanese clinics operate walk-in morning and evening blocks rather than appointments, and close in the middle of the day. If your working day ends in Shibuya at seven, the clinic near your Yokohama flat has usually shut. People discover this when they are already ill. Find the local clinic, note its hours, and know which of the ward's hospitals runs a night and holiday service before you need either.

Source: community-reported

The pension lump-sum withdrawal is real money and departing residents routinely forget it.

Anyone who contributed for at least six months can claim back part of their pension contributions after leaving Japan, applied for within two years of departure. For someone who stayed three or four years this is a meaningful sum. It requires paperwork sent from abroad and a Japanese bank account or a tax representative, which is why doing the groundwork before you leave matters so much.

Source: Japan Pension Service

National Health Insurance premiums are based on last year's income, so year two is the expensive one.

Your first year in Japan is assessed on a Japanese income of zero, which makes premiums minimal and gives a misleading impression of the cost. From the second year they are calculated on your actual earnings and rise sharply, in the same way residence tax does. Budget for the step change rather than being surprised by it.

Source: Yokohama City

Common mistakes to avoid

Assuming health insurance is optional if you are self-employed — it is not.
Enrolling, or trying to, anywhere other than your own Yokohama ward office.
Budgeting from your first-year premium, which is artificially low.
Only finding a clinic when you are already ill and discovering it shuts before your train gets in.
Leaving Japan without claiming the pension lump-sum withdrawal.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.