Not in Japan but live in India which follows essentially a similar system. In India at least, the short answer is the employer doesn't. However, every financia

Not in Japan but live in India which follows essentially a similar system. In India at least, the short answer is the employer doesn't. However, every financial institution that deals with you deducts and prepays some taxes on your behalf and also reports the income. So at the end of the year, it shows up in a report which shows tax deposited and you just have to fill in the sum of that income as "other income". This system is good enough that if you are a salaried person with some investments and some tax deductibles like housing loan, tax filing takes about an hour and also normally doesn't have any surprise element of "you owe the taxman X" It becomes complex only for business owners which is a small minority of the population of any country.