Tax Bill calculator in Python

'''
Tax calc for CA residents. Does not include property tax, child credits etc.
'''

SLABS = [
(10, 9525, 19050),
(12, 38700, 77400),
(22, 82500, 165000),
(24, 157500, 315000),
(32, 200000, 400000),
(35, 500000, 600000)]

CASLABS = [
(1, 7850, 15700),
(2, 18610, 37220),
(4, 29372, 58744),
(6, 40773, 81546),
(8, 51530, 103060),
(9.30, 263222, 526444),
(10.3, 315866, 631732),
(11.3, 526443, 1052886),
]

def fica(inc):
    tax = min(inc, 127200.) * 6.2 / 100.
    tax += min(inc, 200000) * 1.45/100.
    if inc > 200000:
        tax += (inc - 200000) * 2.35/100.
    return tax

def _calc(inc, slabs, highest):
    tax = 0.
    for rate, limit in slabs:
        if inc > limit:
            tax += rate * limit / 100.
            inc -= limit
        else:
            tax += rate * inc / 100.
            inc = 0.
    if inc > 0:
        tax += highest * inc / 100.
    return tax


def calc(inc, issingle):
    if issingle:
        state = _calc(inc - 3992, [(e[0], e[1]) for e in CASLABS], 12.3)
        ded = min(10000, state)
        return fica(inc) + state + _calc(inc - 12000 - ded, [(e[0], e[1]) for e in SLABS], 37.)
    else:
        state = _calc(inc - 7984, [(e[0], e[2]) for e in CASLABS], 12.3)
        ded = min(10000, state)
        return fica(inc) + state + _calc(inc - 24000, [(e[0], e[2]) for e in SLABS], 37.)