A U.S. personal income tax calculator
Python M4 Makefile
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Ben
Latest commit e63ed6f Jun 18, 2018

Readme.md

py1040

This is a tax calculator for one individual U.S. tax return---Internal Revenue Service form 1040 (2015).

basic output from the program Image via: https://twitter.com/konklone/status/711227705996550145

This version's output tries to look more like the tax forms, but there is a visual tree version at https://b-k.github.io/1040.js .

Quick start

  1. Build it, via make. This will pull a copy of 1040.js [ See https://b-k.github.io/1040.js for the attractive front end], and generate Python versions of the forms.
  2. Run python3 taxes.py, which will generate a file named interview.py.
  3. Open interview.py in your text editor, and follow the instructions to provide information about your tax situation.
  4. Run python3 taxes.py again. It will generate inform.py.
  5. Open inform.py and fill in the information from your W-2s and other such sources.
  6. Run python3 taxes.py again. It will calculate your taxes and print the line-by-line calculations to the screen.

Contributing

Each form is represented as a file holding a dictionary of cells, where each cell represents a line of the tax code. The cell includes the text to print, the line number, the calculation to do, whether the cell needs to be part of inform.py, and the list of the cell's parent cells. That dictionary is at https://github.com/b-k/1040.js , in a relatively language-independent format that both the Javascript and Python version parse into functions.

Adding a form, then, consists of transcribing this information for each needed line. This is straightforward, and has proven to take only a few seconds per line. We considered using the XML schemata here: https://www.irs.gov/Tax-Professionals/e-File-Providers-&-Partners/Schemas-Business-Rules-and-Release-Memo-for-MeF-Form-1040-Series-Tax-Year-2015-Version-3_1 but it turns out to be easier to just cut/paste/modify the lines from the PDF forms. Each form should be in one file in the forms directory, which has one python dict that has the same name as the file (and optionally other initializations).

Caveats

This program is not a tax tutor or advisor; there are many other sources that can help you optimize your tax situation. This is just a calculator.

There are many elements of the system that are not yet implemented. I (BK) am not self-employed and don't have a farm, so I have not implemented Schedules C or F. As above, contributing a new form or worksheet is not a massive effort, and if a few more people contribute their situations, we may begin to have a reasonably complete and accurate tax calculator. Until then, please bear in mind that you should verify every calculation done here.

Please note this section from the license, which the license authors felt was important enough to put in all-caps:

THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.

This version was written by BK over the course of a weekend at home, and is therefore not endorsed by or otherwise related to his employer.