PR via Spousal route, how many years of taxes to submit?

Apologies for the elementary question. 

I plan on applying for PR via the Spousal route (already have a 5 year Spouse visa). How many years of 課税・納税証明書 do I submit for me and my wife? I understand that I can apply after 1 year of residency in Japan, so technically you only require 1 year?

Thank you