noun
income certificate; certificate of earnings
An official document issued by a government office (often a city or ward office) that certifies a person's income for a given year. Commonly required for tax purposes, welfare applications, or loan procedures.
保育園の申し込みに所得証明書が必要です。
An income certificate is required to apply for a nursery school.
市役所で所得証明書を発行してもらった。
I had an income certificate issued at the city hall.
Compound of 所得 (income) + 証明書 (certificate). The word follows standard Sino-Japanese word formation.