Federal income tax calculator for procrastinators

Today is Tax Day!

Oops.

So you're probably still completing your return and need a calculator for when you get to Line 44.

Given an input of taxable income (US$, accurate to 2 decimal places) and a string representing filing status, output the amount of tax (also US$ to 2 decimal places).

Filing status will be one of S, MFJ, QW, MFS, or HH for Single, Married Filing Jointly, Qualified Widow(er), Married Filing Separately or Head of Household, respectively.

Example Inputs:

0.00 S
10000.00 MFJ
100000.00 MFS
1000000.00 QW


Example Outputs corresponding to above inputs:

0.00
1000.00
21525.75
341915.90


Summary of tax tables.

Married Filing Jointly and Qualified Widow(er)

Income Interval Tax [ $0,$18450] 10% ( $18450,$74900] $1845 + 15% of the excess over$18450 ( $74900,$151200] $10312.50 + 25% of the excess over$74900 ($151200,$230450] $29387.50 + 28% of the excess over$151200 ($230450,$411500] $51577.50 + 33% of the excess over$230450 ($411500,$464850] $111324 + 35% of the excess over$411500 ($464850,$∞] $129996.50 + 39.6% of the excess over$464850

Income Interval Tax [ $0,$13150] 10% ( $13150,$50200] $1315 + 15% of the excess over$13150 ( $50200,$129600] $6872.50 + 25% of the excess over$50200 ($129600,$209850] $26722.50 + 28% of the excess over$129600 ($209850,$411500] $49192.50 + 33% of the excess over$209850 ($411500,$439000] $115737 + 35% of the excess over$411500 ($439000,$∞] $125362 + 39.6% of the excess over$439000

Single

Income Interval Tax [ $0,$9225] 10% ( $9225,$37450] $922.50 + 15% of the excess over$9225 ( $37450,$90750] $5156.25 + 25% of the excess over$37450 ( $90750,$189300] $18481.25 + 28% of the excess over$90750 ($189300,$411500] $46075.25 + 33% of the excess over$189300 ($411500,$413200] $119401.25 + 35% of the excess over$411500 ($413200,$∞] $119996.25 + 39.6% of the excess over$413200

Married Filing Separately

Income Interval Tax [ $0,$9225] 10% ( $9225,$37450] $922.50 + 15% of the excess over$9225 ( $37450,$75600] $5156.25 + 25% of the excess over$37450 ( $75600,$115225] $14693.75 + 28% of the excess over$75600 ($115225,$205750] $25788.75 + 33% of the excess over$115225 ($205750,$232425] $55662 + 35% of the excess over$205750 ($232425,$∞] $64998.25 + 39.6% of the excess over$232425

• I'd like to see "golf the entire functionality of TurboTax" – qwr Apr 20 '16 at 2:39
• @qwr I don't think golfing works well with the whole "fix it every year" that tax code has to be – CAD97 Apr 20 '16 at 2:48
• @CAD97 Nonsense, even this problem is year dependent! – qwr Apr 20 '16 at 2:56

Python 3, 427382317309308 275 bytes

-45 bytes by figuring ternary expression out (wow that's a long line); thanks Maltysen

-65 bytes, now with iteration for DRYer code!

-8 bytes by in-lining tuple variables; thanks Majora

-1 byte by using a dict rather than ternary chain; thanks again Maltysen

-33 bytes by reusing MFS step as half of MFJ/QW and calculating tax an order of magnitude larger; thanks Neil

def f(i,s):
t=i;k={'MFS':(9225,28225,38150,39625,90525,26675),'S':(9225,28225,53300,98550,222200,1700),'HH':(13150,37050,79400,80250,201650,27500)}
for x in range(6):
i-=k[s][x]if s in k else k['MFS'][x]*2
if i>0:t+=(.5,1,.3,.5,.2,.46)[x]*i
return'{:.2f}'.format(t*.1)


If I had been thinking I would have made the function signature t(a,x), but I guess I'll stick with function(income, status).

When code is barely undertstood by the writer, is that when you win at golf?

• you can save by changing the ifs into a series of ternaries and having only one a,b,c,d,e,f= – Maltysen Apr 20 '16 at 0:12
• @Maltysen And now since I figured out how to iterate to save repetition of taxation, I only have to assign the tuple :) – CAD97 Apr 20 '16 at 0:37
• You can shave off 10 bytes by replacing c and r with the literal tuple, because they are only used once. (tested, working; even works with the long c line) – Majora320 Apr 20 '16 at 0:49
• you can prolly save more with either dicts or indexing and slicing. – Maltysen Apr 20 '16 at 0:58
• "When code is barely undertstood by the writer, is that when you win at golf". Almost. The next step is to port your code to pyth :) – Digital Trauma Apr 20 '16 at 2:47

JavaScript (ES6), 223 bytes

(i,s)=>(({MFS:a=[x=9225,y=28225,38150,39625,90525,26675],S:[x,y,53300,98550,222200,1700],HH:[13150,37050,79400,80250,201650,27500]}[s]||a.map(b=>b*2)).reduce((t,b,j)=>t+((i-=b)>0&&i*[.5,1,.3,.5,.2,.46][j]),i)*.1).toFixed(2)


Basically a port of CAD97's Python answer, but I saved 4 bytes by multiplying the tax by 10 during the calculation and 11 bytes by reducing the duplication in the tax bands.

• @DigitalTrauma Oops I don't develop on the machine on which I have PPCG open so sometimes I typo when copying the code across. (The beauty of Code Golf is that I want to copy as little code as possible!) – Neil Apr 20 '16 at 16:41
• Good. Works for me now in both firefox and chrome. – Digital Trauma Apr 20 '16 at 16:46