Indonesia income tax calculator, assuming PTKP single, no dependants.

pajak.py

import sys

MILLION = 10 ** 6
PTKP = 54 * MILLION
RATES = [
    (0.05, 50 * MILLION),
    (0.15, (250 - 50) * MILLION),
    (0.25, (500 - 250) * MILLION),
    (0.3, float('inf')),
]    

def calculate(income):
    pkp = income - PTKP
    tax = 0
    for rate, amount in RATES:
        if pkp <= 0: break
        tax += min(pkp, amount) * rate
        pkp -= min(pkp, amount)

    return tax

if __name__ == "__main__":
    try:
        int(sys.argv[1])
    except:
        print 'usage: pajak.py [income (in millions)]'
    else:
        tax = calculate(int(sys.argv[1]) * MILLION)
        print 'Rp', tax / MILLION, 'juta'