Severance pay with withholding income and inhabitant tax

Example, Say Severance Pay is JPY3,471,360

Withholding Income Tax Deduction
1. [3,471,360 – (400,000 x3)] x 1/2 = 1.135.680 = 1.135.000 (Round Down)
2. 1,135,000 x 5% = 56,750
3. 56,750 x 102.1% (1.021) = 57,941.75 = 57,941 (Round Down)

Withholding Inhabitant Tax Deduction
1. [13,471,360 -400,000 x 3) )]x 1/2 =1,135,680
2. 1,135,680 x 6% = 68,140.8 = 68,100 (Round Down)
3. 1,135,680 x 4% = 45,427.2 = 45,400 (Round Down)
4. 68,100 + 45,400 = 113,500

Net Payment JPY3.299,919 (=3.471,360 – 57,941-113,500)