Open-source Tax Solver (OTS)

April 12, 2018
- Project -
-   - Updated for the most recent year's taxes.

OpenTaxSolver (OTS) is a free, safe + secure program for calculating Tax Form entries for Federal and State personal income taxes. It automatically fills-out and prints your forms.


The updated version of OTS for this year's taxes is posted. (Version 15.07 - 2017 Tax-Year)

As in prior years, the download package covers the most popular US 1040 with Schedules A, B, C, D, along with the 6251 (AMT) & 8949 forms. All of the Federal Forms and Schedules are generated from the main US-1040 program. - except for Schedule-C, which is done as a separate program in the set. OTS also does State Taxes for California, New Jersey, North Carolina, Ohio, Pennsylvania, Virginia, New York, and Massachusetts.

This year there are several improvements.

  • Switched all forms to the new universal PDF fill-out method. Should work reliably on all PDF viewers. Enables more complete form fill-out, including check-marks, etc.. *All* form-fields can now be easily changed or edited with Libre-Office Draw.
  • Now constructs single PDF document containing all, and just, the relevant pages for a given return.
  • Improved prompts/comments in many of the tax-forms.
  • More option spinners in GUI for many of the forms. These provide convenient selection of available answers for questions needing specific choices.
  • Further simplified GUI operation.
  • Added unlimited extra-pages overflow capability for Fed-1040 Schedules B+D.
  • All programs report tax-bracket and effective tax-rate for your information. In case of underpayment, shows percent underpaid.

OTS has two movies on Youtube:
  1. 1-minute OTS Overview - Quick brief on what OTS does.
  2. OTS Introduction Video - How to download, install, & use OTS.
The first one shows basically what OTS does and how it works -- good to watch if you are deciding whether to download it. The second one is a helpful instructional guide for first time users. If we get good feedback that these are helpful, then we will add more movies on requested topics.

Saves time by filling out the answers onto the actual government PDF tax-forms. Auto-Fillout of PDF Forms is now available for all forms supported OTS (Federal & State). You will see the Auto-Fillout option when you click Print.

Mailing List:
Join the OTS mailing list to receive important messages about new updates and fixes: Subscribe to New OTS Releases & Updates. Very low traffic. (You can remove yourself from the list at anytime by sending an email from your email account to with the words "Remove me." as the first words in the subject line.)

After you use OTS this year, take a few minutes to fill out the Anonymous User Survey. Your feedback will improve OTS. See Survey Results received so far ....

In the USA this year, Federal Taxes must be post-marked, on or before, Tuesday, April 17, 2018. Most State Taxes will be due that day as well, or later.     If you file for an extension, then your final form(s) generally must be postmarked by Monday, October 15, 2018.

You can always check the OTS Blog for status updates.   All -updates, -notifications of issues, and -contributions of additional forms -- from you, the community -- are much appreciated!     Special thanks again to all contributors.

Also, as the New Year starts, remember that the Payroll Withholding Calculator is helpful for calculating adjustments to your weekly pay-check deductions throughout the year, to avoid under-withholding or over-withholding.

OTS FaceBook Page:    
Please visit and like-us on our FaceBook page.

Several users have asked how they can help support OTS, even if not technically inclined. So a fund-drive has been started under Please-Fund-Us to support continued updates and improvements to this project. Visit the fund-drive page at: Please-Fund-US
The page explains how the funds will be used. No donation amount is too small. Every bit is helping.


The OTS tax package is intended to be used with the Tax booklets published by your government for determining what numbers you need to enter, and then it assists you in doing the otherwise tedious calculations while showing the intermediate and final numbers. It takes care of the tedious and error-prone work.

OTS is intended for those who are comfortable doing their own taxes - especially those who have previously done their taxes and basically understand how to fill out the forms. OTS does much of the math for you.

The OTS_GUI is the default Graphical User Interface. The GUI allows you to conveniently enter tax data, and then invokes the appropriate text program when you press the Compute button. Alternatively, you can directly enter your tax data by editing the text files with your favorite text editor, and then process it by invoking the appropriate tax-solver program. Most people nowadays use the GUI, so that is the default mode according to instructions in the package.

Behind the GUI is a text-window. It shows the actual commands the GUI uses when you press buttons. You can look at that, if you wish, to learn how to run the same commands directly from your command-line. Since the GUI is fairly self-explanatory, the detailed documentation focuses on how the core text programs work, for those interested.


Example screen shots of OTS_GUI.

Although originally created for US 1040 tax forms, the core routines have also been used to solve other tax forms, and for other countries or states. Some error checking is included.

While the OTS programs developed over the past fifteen years, results have often been checked against commercial packages. The answers produced by OTS typically matched to within a dollar or so, differing sometimes by rounding effects. Certainly your mileage may vary. Always double-check your tax forms!!


Download OpenTaxSolver

OpenTaxSolver for this year's taxes (2017 Tax Year) can be downloaded from:
        -   - (this year's version)

Source code and compiled executables are available in all download packages. Example form-data files are included for all forms. Typical package size is about ~5-10 MB (small by today's standards), which includes all the PDF forms. Prior year's versions are available at Downloads.

Packages for Linux/Unix/MaxOSx are tar-gzip (.tgz), while packages for Microsoft are zip files. To unpack, double-click on the package. Or from a command-line,   tar xfz package.tgz   or   unzip . Will unpack into a directory of the same name. (To see contents prior to unpacking, tar tvfz package.tgz   or   unzip -l .)

Tar packages contain precompiled executables for Linux (32-bit and 64-bit), and MacOSx.
Zip packages contain precompiled executables for Microsoft PCs.
Source code and compilation instructions are also provided in all versions.
(Uninstall by simply deleting the directory. No registry entries are made.)

Other Links

Feedback welcome.

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Aston Roberts -