
Ask HN: Open source tax calculator? - zyncl19
I want to create a budget application for my own personal use cases. I&#x27;d like to be able to calculate both withholding and end of the year taxes. Are there any open source libraries that would help me do this? I&#x27;d prefer python or C++, but would work with any language.
======
Jtsummers
I wrote a withholdings calculator in Excel for myself this past year, I can
try to clean it up and post it somewhere. I also developed it to the point
that it gives me a very accurate estimate of my final tax refund/owed amount
(I added fields to allow me enter interest, dividend, and other income). [0]
describes the withholding tables for 2019. Income tax withholding starts on
page 44 and is the most relevant. Social security is 6.2% of income up to
$132,900 (0% over that) and Medicare is 1.45%. It's actually a pretty
straightforward task to produce regardless of language.

Those plus your local state income tax withholding tables should be enough to
get started on making something like this yourself.

The open tax solver linked looks good, but their payroll calculator assumes
weekly pay which will get you in the ballpark but won't be accurate if you are
paid less frequently (you can't even just double its numbers for biweekly pay,
due presumably to rounding issues).

Py1040 looks ok as a start but will also only cover your end of year tax
situation. It's also using hardcoded tax tables which is unfortunate since
they seem to have been last changed in 2016 and so is wrong for 2018 and
forward. Using external tables to drive it would make it much easier to
update.

The IRS Withholding calculator will, of course, be very accurate but you can't
really embed it into anything else. And if your tax situation is simpler you
can elide a lot of details.

[0] [https://www.irs.gov/pub/irs-pdf/p15.pdf](https://www.irs.gov/pub/irs-
pdf/p15.pdf)

------
ksherlock
Is the IRS Withholding calculator good enough?

[https://www.irs.gov/individuals/irs-withholding-
calculator](https://www.irs.gov/individuals/irs-withholding-calculator)

------
BasicObject
[http://opentaxsolver.sourceforge.net/](http://opentaxsolver.sourceforge.net/)

------
plg
[https://github.com/b-k/py1040](https://github.com/b-k/py1040)

