新旧版个税计算

tax.py

# -*- coding: utf-8 -*-

import sys

# 旧版个税表
# 应税工资，税率，速算扣除额度，最少缴税额度
old_table = [
    (3500, 0.03, 0, 0), # 
    (5000, 0.1, 105, 45),
    (8000, 0.2, 555, 345),
    (12500, 0.25, 1005, 1245),
    (38500, 0.3, 2755, 7745),
    (58500, 0.35, 5505, 13745),
    (83500, 0.45, 13505, 22495)
]

# 新版个税表
new_table = [
    (5000, 0.03, 0, 0),
    (8000, 0.1, 210, 90),
    (17000, 0.2, 1410, 990),
    (30000, 0.25, 2660, 3590),
    (40000, 0.3, 4410, 6090),
    (60000, 0.35, 7160, 12090),
    (85000, 0.45, 15160, 20840)
]


def get_tax_by_incoming(incoming, is_new):
    ''' 通过应税工资计算出个税值 '''
    table, base = (new_table, 5000) if is_new else (old_table, 3500)
    # 个税起征点
    if incoming <= base:
        return 0
    for index in range(len(table)):
        before, after = table[index], (table[index + 1][0] if index < len(table) - 1 else sys.maxsize)
        if before[0] <= incoming < after:
            return (incoming - base) * before[1] - before[2]
        continue


def get_incoming_by_tax(tax, is_new):
    ''' 通过个税值计算出应税工资 '''
    table, base = (new_table, 5000) if is_new else (old_table, 3500)
    for index in range(len(table)):
        before, after = table[index], (table[index + 1][3] if index < len(table) - 1 else sys.maxsize)
        if before[3] <= int(tax) < after:
            return (tax + before[2]) / before[1] + base


def diving_tax(tax):
    current, delta = None, None
    for i in range(1, 10, 1):
        old = get_incoming_by_tax(i * tax / 10, False)
        new = get_incoming_by_tax((10 - i) * tax / 10, True)
        if delta is None or delta > abs(new - old):
            delta = abs(new - old)
            current = (old, i * tax / 10, new, (10 - i) * tax / 10)
    return current


if __name__ == "__main__":
    for incoming in [3500, 5000, 8000, 12500, 38500, 58500, 83500]:
        tax = get_tax_by_incoming(incoming, False)
        inc = get_incoming_by_tax(tax, False)
        print(incoming, tax, int(inc) == incoming)