How to calculate the amount of national health insurance tax ( Kokumin kenkou hoken ryou = 国民健康保険料 ) in Japan

The calculation formula of national health insurance tax is different from each city.

So, in this page this is just for reference.

( This calculation formula is based on Setagaya ward, Tokyo, year of 2015. )

1 Check the amount of income ( Shotoku kingaku ).

The amount of income = earnings ( shuu nyuu ) – deductible expense ( Keihi ).

In the case of salaried workers.

The amount of income = The amount of salary – employment income deduction ( Kyuuyo shotoku koujo ).

In the case of self employee.

The amount of income = The amount of sales – deductible expense.

This is a part of application form for blue income tax return.

In the case of salaried worker.

This is a part of slip of withholding income tax.

２ Deduct 330,000 yen from the amount of income and calculate base amount.

Assumed that you are a self employee and have a wife and a child.

All persons are enrolled in national health insurance.

You ( 40 years old ) are managing business without legal entity and your wife ( 39 years old ) sometimes assist your business.

You pay salary to your wife.

The amount of your sales is 12,000,000 yen per a year.

Deductible expense other than salary to your wife : 6 million yen.

The amount of your wife’s salary : 1 million yen.

The amount of business income : 5,000,000 yen.

( 12,000,000 yen. – 6,000,000 yen – 1,000,000 yen = 5,000,000 yen )

Your base amount : 6,000,000 yen – 330,000 yen = 5,670,000 yen.

Your wife : The amount of income is 1,000,000 yen.

1,000,000 yen – 650,000 yen ( <a href=””>employement income deduction = kyuuyo shotoku koujo</a> ) – 330,000 yen = 20,000 yen.

This is base amount of your wife.

Child : 12 years old.

The amount of income : 0 yen.

Total base amount : 5,670,000 yen + 20,000 yen = 5,690,000 yen.

３ Let’s calculate the amount of per capita basis ( Kintou wari ).

You can calculate the amount of per capita basis ( Kintou wari gaku ) based on the number of family members.

(a) The number of family member × 33,900 yen 3 persons ×33,900 yen ＝101,700 yen.

(b) The number of family member × 10,800 yen 3 persons ×10,800 yen ＝ 32400 yen.

(c) The number of family member of age of 40 ～64 × 14,700 yen 1 person ×14,700 yen ＝14,700 yen.

Total (a)+(b)+(c) = 101,700 yen＋32,400yen＋14,700 yen＝148,800 yen

This amount is called taxation on per capita basis ( Kintou wari gaku ).

4 Let’s calculate the amount of taxation on per income basis ( Shotoku wari gaku ).

(d) Base amount of 5,690,000 yen ×6.45% ＝367,005 yen.

(e) Base amount of 5,690,000 yen ×1.98%＝112,662 yen.

(f) The amount of person his/her age is from 40 ～64 ×1.50% 5,670,000 yen×1.50%＝85,050 yen

Total (d) + (e) + (f) = 367,005 yen + 112,662 yen + 85,050 yen = 564,717 yen.

This amount is called taxation on per income basis ( Shotoku wari gaku).

5 Let’s add up taxation on per income basis ( Shotoku wari gaku ) and taxation on per income basis ( Shotoku wari gaku).

148,800 yen + 564,717 yen = 713,517 yen.

This amount is annual national health insurance tax.

6 Maximum amount of national health insurance tax.

There is maximum amount of national health insurance tax.

(a) + (d) = 520,000 yen

(b) + (e) = 170,000 yen

(c) + (f) = 160,000 yen

Annual maximum amount : 850,000 yen.

The amount of national health insurance differs depending on city you live.

According to city, the amount differs more than 200,000 yen per a year.