How to get income certificate（所得証明書）

What is income certificate?
Income certificate usually describes how much annual (January 1 to December 31) income and amount of tax paid was. Issued by the municipality where you have registered as resident.
However, the form is not unified, The name could be different depending on the city. such as taxed certificate（課税証明書）, tax certificate（税証明書）, or tax income certificate（税所得証明書）, and the description also varies by cities.

If you have moved
The income certificate will be issued from the municipality where you are registered, but if you have moved to another city, it will be a little complicated.
The income certificate only be issued in the municipality where your registration was on january 1st of the year that you want to apply.

Example
You have moved from City A to City B in May 2019

Your current resident registration is city B, but at the time of January 1st 2019, you had a resident registration in City A, so the application is not to the city B but to the city A.

If you want to obtain an income certificate for 2019→ Apply to City A
If you want to obtain an income certificate for 2020→ Apply to City B

Income certificates for 2019 describes income and tax from January to December 2018,
And in most municipalities you could apply from June every year.

Moreover, it seems not to be able to do until it has to be after the middle of June when the income proof of the previous year is issued.

How to apply income certificate
There are three ways to apply income certificate: “city office”, “mail”, and “convenience store”.

1. Directly go to the city office
What you need
Fill out the application form
Identification document (passport, residence card, etc.)
Fees (depending on each city)
A seal might be required depending on the city.

Example of application form: Shinagawa Ku（品川区）
https://www.city.shinagawa.tokyo.jp/contentshozon2019/ininnjoujuuminzeinouzei.pdf

When other people would apply instead of you

If your relative living with you apply it, they will need an identification document.
If nonrelative apply it, they will need an identification document and a “power of attorney”

As for “power of attorney”, there is no fixed style, but there are some municipality where you can download the model of the power of attorney.
Example of a power of attorney: Shinagawa Ku（品川区）
https://www.city.shinagawa.tokyo.jp/contentshozon2019/ininnjoureiwa.pdf

2. Use the mail service
What you need
Application documents
A copy of the identification document
a postal note(郵便小為替)
Envelope for replying

You can buy postal note (郵便小為替) only at the post office or the Japan Post Bank(ゆうちょ銀行). In addition, a fee of 100 yen is required.

3. Use the multi-copy machine at convenience stores
Some municipalities offer automatic certificate Issuance services at convenience stores.
You can issue a certificate daily from 6:30 to 23:00 using the convenience store’s multi-copy machine.

How to issue a certificate by multi-copy machine.

Select “Administrative Service” from the touch panel of the multi-copy machine
Select Certificate Service
Set ”My Number Card”
Select a city
Enter your password for “my number card”
Choosing a certificate type
Enter the required information and the number of required sheets
Put fees
Receive the certificate

Notes
There is a municipality that does not offer at the convenience store Issuance services. In addition, what certificate you could obtain at the convenience store is depends on the city.
Some municipalities do not support income certificates,
J-LIS (Local Government Information Systems Organization)
You can search for available cities.
https://www.lg-waps.go.jp/01-04.html

If you do not have a resident card, you will not be able to use the convenience store Issuance services.