RetireJapan

Pretty sure the employee contribution falls into post-tax income because I started contributing a couple years ago to max out the 55000 yen allowed per month. When checking my pay statements I see no difference in taxes withheld. The shakai hoken is identical in the months I contributed vs the months when I did not contribute.

Also, at the end of the year I get a statement that shows "gross income" and "taxable income". I subtracted the latter from the former and divided that by 12 to see what amount was not being taxed. The monthly non-taxed amount was identical to my monthly commuter pass allowance which is an odd number like 9433 yen (or something) so it definitely had to be that. For that reason, I believe my DC contributions are taken from post-tax income.

I have all my income calculated in an excel sheet (with all the taxes, and all), and as far as I can tell my DC contribution also seems to be taken from post-tax income (my pay slip shows the taxable income and it does not count the DC amount).

Having said that my calculated monthly income tax (using the NTA table https://www.nta.go.jp/publication/pamph ... 021/02.htm)
is slightly higher than the income tax I actually pay (I pay 90 yen less than I should be paying according to the table, but the amount I actually pay does not exist on the table so it is not like I'm in a different bracket than expected).
So there is definitely some hidden discount which I've not been able to pinpoint yet, which I'm pretty sure is linked to the DC contribution.