Withholding tax on remitting payment to outside Japan
When you pay fee to a Non-Resident individual or a Foreign company, you have to check whether withholding tax deduction is required by the Japan tax law at any time.
Principle：20% of withholding tax deduction is mandatory.
20% of withholding tax deduction is mandatory when you pay fee which is attributable Japan source income to Non-resident indivudial or Foreigin company under the Japanese individual tax law.
Relief can be applied by Application fro income tax convention. e.g. Royalty
Provided there is a tax treaty between Japan and your country, Non-resident individuals or non-resident companies, which receives Japan source income deducted withholding tax at source, can file APPLICATION FORM FOR INCOME TAX CONVENTION so that to enjoy relief or exemption on payments.
The APPLICATION FORM should be filed before a pay day. Otherwise 20% of withholding tax is deducted.
However, if you file after payment, you can refund it by filing refund application form accordingly.
Japanese tax certificate is necessary when you apply Foreign tax credit in your home country.
You can obtain a tax certificates from Japan tax office.Application Form (In Japanese language)