Option Explicit
'-----------------------------------------------
'退職所得控除
Function taisyoku_syotoku_kozyo(kinzoku_nen As Integer, Syogai_s As Boolean) As Long
    Dim c As Long
On Error GoTo Err_taisyoku_syotoku_kozyo
    
    c = Application.Max(kinzoku_nen, 2) * 400000 + Application.Max((kinzoku_nen - 20), 0) * 300000
    If Syogai_s = False Then '障害でないなら
        c = c
    ElseIf Syogai_s = True Then '障害なら１００万円追加
        c = c + 1000000
    Else
        c = 0
        MsgBox "退職所得控除を０として計算します", vbOKOnly & vbCritical
    End If
    
    taisyoku_syotoku_kozyo = Application.Max(c, 0)
    Exit Function

Err_taisyoku_syotoku_kozyo:
    MsgBox Err.Description, vbOKOnly & vbCritical
       
End Function

'-----------------------------------------------
'退職所得税額
Function taisyoku_syotoku_zei(taisyoku_kin, kozyo)
On Error GoTo Err_handler
    Dim c, d As Long
    '課税退職所得金額
    c = Application.ROUNDDOWN((taisyoku_kin - kozyo) / 2, -3)
    '税額の計算
    If c <= 3300000 Then
        d = c * 0.1
    ElseIf c <= 9000000 Then
        d = c * 0.2 - 330000
    ElseIf c <= 18000000 Then
        d = c * 0.3 - 1230000
    'ElseIf c <= 30000000 Then
    '    d = c * 0.4 - 3030000
    ElseIf 18000000 < c Then
        d = c * 0.37 - 2490000
    Else
        d = 0
    End If
    taisyoku_syotoku_zei = Application.Max(d, 0)
    Exit Function
    
Err_handler:
    MsgBox Err.Description, vbOKOnly & vbCritical
    
End Function


'-----------------------------------------------
'退職所得にかかる道府県民税
Function kenmin_zei(taisyoku_kin)
'引数は、退職所得控除後の金額(退職金−退職所得控除）
On Error GoTo Err_handler
Dim c, d As Long
'基準額の算定
If taisyoku_kin < 8000 Then
    c = 0
ElseIf taisyoku_kin < 252000 Then
    d = (taisyoku_kin - 8000) Mod 4000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 780000 Then
    d = (taisyoku_kin - 252000) Mod 8000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 1560000 Then
    d = (taisyoku_kin - 780000) Mod 12000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 2600000 Then
    d = (taisyoku_kin - 156000) Mod 16000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 8000000 Then
    d = (taisyoku_kin - 2600000) Mod 20000
    c = taisyoku_kin - d
ElseIf 8000000 <= taisyoku_kin Then
    c = Application.ROUNDDOWN(taisyoku_kin / 2000, 0) * 2000
End If

Dim e

'道府県民税の計算
If 8000 <= c And c <= 4000000 Then
    e = Application.ROUNDDOWN((c * 0.01) * 0.9, -2)
ElseIf c <= 13998000 Then
    e = Application.ROUNDDOWN((c * 0.01) * 0.9, -2)
ElseIf 14000000 <= c Then
    e = Application.ROUNDDOWN((c * 0.015 - 70000) * 0.9, -2)
Else
    e = 0
End If

kenmin_zei = Application.Max(e, 0)
Exit Function

'エラー処理
Err_handler:
    MsgBox Err.Description, vbOKOnly & vbCritical
End Function


'-----------------------------------------------
'退職所得にかかる市町村民税
Function simin_zei(taisyoku_kin As Long)
'引数は、退職所得控除後の金額(退職金−退職所得控除）
On Error GoTo Err_handler
Dim c, d As Long
'基準額の算定
If taisyoku_kin < 8000 Then
    c = 0
ElseIf taisyoku_kin < 252000 Then
    d = (taisyoku_kin - 8000) Mod 4000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 780000 Then
    d = (taisyoku_kin - 252000) Mod 8000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 1560000 Then
    d = (taisyoku_kin - 780000) Mod 12000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 2600000 Then
    d = (taisyoku_kin - 156000) Mod 16000
    c = taisyoku_kin - d
ElseIf taisyoku_kin < 8000000 Then
    d = (taisyoku_kin - 2600000) Mod 20000
    c = taisyoku_kin - d
ElseIf 8000000 <= taisyoku_kin Then
    c = Application.ROUNDDOWN(taisyoku_kin / 2000, 0) * 2000
End If

Dim e

'市町村民税の計算
If 8000 <= c And c <= 4000000 Then
    e = Application.ROUNDDOWN((c * 0.015) * 0.9, -2)
ElseIf c <= 13998000 Then
    e = Application.ROUNDDOWN((c * 0.04 - 100000) * 0.9, -2)
ElseIf 14000000 <= c Then
    e = Application.ROUNDDOWN((c * 0.05 - 240000) * 0.9, -2)
Else
    e = 0
End If
simin_zei = Application.Max(e, 0)

Exit Function

'エラー処理
Err_handler:
    MsgBox Err.Description, vbOKOnly & vbCritical
End Function