Open-source Tax Solver (OTS)

November 8, 2017
- Project -
-   - Updated for the most recent year's taxes.

OpenTaxSolver (OTS) is a free, safe + secure program for calculating Tax Form entries and tax-owed or refund-due, such as Federal or State personal income taxes.  


Work has begun on the updates for the upcoming year's version.

As in prior years, the download package will cover 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 will do the State Taxes for California, Pennsylvania, New Jersey, North Carolina, Ohio, Virginia, New York, and Massachusetts.

Last year year there were several improvements.

  • An optional set of lines has been added to supply your name and address only for the auto-fillout option. You can leave these lines blank. They do not affect any calculations. But if you fill them in, and you select auto-fillout, it will place your name and address on the forms, so you do not have do it manually. Otherwise, you can always enter your name and address manually on the final version of your forms.
  • We improved the automatic selection of your PDF viewer for the Auto-PDF-Fillout feature. This was a problem for some users last year.
  • For the Federal 1040:
    • Added a line (L8b) for entering Tax-Exempt Interest. This is only used and needed for Social Security Benefits calculations. It is not used if you are not yet receiving Social Security payments.
    • OTS now does the Social Security Benefits worksheet, for whom this applies. This had been much-requested. It now calculates the Line-20b entry for you. (Your SocSec benefits entry for Line 20 changes. Previously you entered the amount for Line 20b, which was the result from the SocSec Worksheet. Now you just enter amounts for Line 20a, which are the raw amounts from the box 5's of all your SSA-1099 and RRB-1099 forms. )
  • Added PDF Auto-fillout for five (5) more States - Virginia, New Jersey, New York, Massachusetts, and North Carolina. Added California Sched-CA form to auto-fillout. Now all forms supported by OTS have the Auto-Fillout capability!!
  • All programs now report tax-bracket and effective tax-rate for your information. In case of underpayment, OTS now shows percent underpaid. (More than 10% underpayment may result in penalties in some cases.)
  • The PDF form programs now place commas in large dollar amounts (except where disallowed).
  • The OTS opening screen and file-browser are now more intuitive for new users, and easier to use. It will prevent some common mistakes in opening or saving tax-files.
  • Help buttons have been added to the GUI. These provide information about the version of the OTS package, some brief instructions on how to use it, and links back to our web-site for additional help, information, and updates.

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.

Last year's release extended the Auto-Fillout option. It saves time by filling out many of the numbers 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. (Next to the Auto-Fillout button is a button to select your favorite PDF-Viewer.)

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 click on the updated Anonymous OTS User Survey. Your feedback will improve OTS. Some questions are new - so re-take it even if you have answered in the past. Next month we will again display a page summarizing the results.

In the USA next year, Federal Taxes are to 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 particularly useful in combination with the Adobe PDF Fill-In forms distributed by the government agencies.

OTS is helpful 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 last year's taxes (2016 Tax Year) can be downloaded from:
        -   - (last 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 tfz 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.

Get Open Tax Solver at Fast, secure and Free Open Source software downloads   .   .   .     .   .   .  

Aston Roberts -