How much more do I need to charge as a contractor? (Ballpark figure for Japan)

Question

I'm considering to change from a regular employment contract 契約社員 to an independent contractor 業務委託契約 arrangement.

Comparing working directly as an employee by a company and as an independent contractor for the same job, some costs formally on on the company now falls on me as the contractor instead. I guess health insurance and tax are examples in this category but I assume there are more.

How much more do I need to charge as a contractor compared to the salary to get the same bottom line?

(For a yearly salary figure let's say about 600万円 - 10000万円 for this example and ignore bonus, overtime etc etc in this equation for simplicity, )

Answer 1

From what I learned, we were to estimate our employee costs as 2.5x base salary when calculating 正社員 versus 業務委託契約. However, it depends on what insurance scheme you're going to be on, which might depend on your age or other factors. You'll also want to factor in costs/depreciation for equipment, internet, accountants, etc.