Canadian income tax calculation.

This package provides a library and executable to fill out incomplete Canadian tax forms in FDF format and to populate all fields therein that can be automatically calculated from the rest of the form.

Canadian Income Tax

This Haskell package consists of a library and a couple of executables to complete the Canadian income tax forms.

Command line

There's a command-line executable named complete-canadian-taxes. The way to use it is as follows:

1. Download the fillable PDF forms from the canada.ca Web site.

2. Fill in the downloaded forms:

   • T1 is supported and mandatory for all provinces and territories.
   • If you're a resident of British Columbia or Ontario, you can also fill in the 428 and 479 forms for the province.
   • If you're a resident of Alberta or Manitoba, you can also fill in the 428 form for the province.
   • For all the other provinces only the T1 form and several federal schedules are getting completed at this time.

   In any case, don't bother filling in any fields that are calculated from other fields in the supported forms, that part will be performed automatically. You also don't need to fill any fields that don't matter for the rest of the form: your name, SIN, and other identifying information fall into this category, except for the birth date and marital status which may affect your tax credits.

3. Save the filled-in PDF form(s).

4. Run

   complete-canadian-taxes <province code> --t1 50??-r-fill-23e.pdf -o completed/
   

   where <province code> is the two-letter code of the province or territory (AB, BC, QC, etc), 50??-r-fill-23e.pdf is the T1 form file you previously saved and completed/ is the name of the output directory; feel free to change the names. If applicable, you can also supply the 428 and 479 form with the command-line options of the same name. For example, to complete all three forms for Ontario (ON) taxes the full command line would be

   complete-canadian-taxes ON --t1 5006-r-fill-23e.pdf --428 5006-c-fill-23e.pdf --479 5006-tc-fill-23e.pdf -o completed/
   

   The usual --help option will give you the full list of all supported forms.

At this point my job is done. The rest is all in your hands:

5. Carefully examine the completed PDF forms. The executable comes with no warranty and has not been verified by CRA. The responsibility for the correctness of the tax return is still yours. If you notice any problem in the way the forms were completed please report the issue.

   If at any point you find you made a mistake in your initial form entry, or you want to adjust it for any reason, you can make the adjustments either on the forms you kept from step #2 or on the final forms, and feed them back in step #3. The executable will overwrite all calculated fields with their proper values.

6. Once you're satisfied with the forms: add your ID and print the tax return, sign it, then send it to CRA by mail along with your other documents. At some point they'll hopefully leave the 19th century and let us digitally file the same information they accept on paper, but their NETFILE protocol is not open to the public so far.

Design notes and hints

The executable complete-canadian-taxes follows the Unix philosophy of doing one well-defined task and no more. It doesn't attempt to guide you, the user, through the entire process of filing the taxes. It merely performs the task that is easy to automate, and therefore also the most boring. It's not likely to make the tax-filing process a joy, but it should at least reduce the drudgery.

Manual FDF mode

The executable complete-canadian-taxes automatically invokes pdftk to convert between PDF and FDF files. It needs to be installed and in the executable path. If you'd prefer to handle the conversions manually, you can replace step 4 with the following procedure:

41. Run

    pdftk 5006-r-fill-23e.pdf generate_fdf output 5006-r-fill-23e-filled.fdf
    

    where 5006-r-fill-23e.pdf is the file you previously saved and 5006-r-fill-23e-filled.fdf is the name of the output file; feel free to change them.

42. Run

    complete-canadian-taxes <province code> --t1 5006-r-fill-23e-filled.fdf -o completed/
    

    to complete all the field calculations and store the result in the output file completed/5006-r-fill-23e-filled.fdf.

43. Run

    pdftk 5006-r-fill-23e.pdf fill_form completed/5006-r-fill-23e-filled.fdf output 5006-r-fill-23e-completed.pdf
    

    to transfer the FDF field values from the previous step to the new PDF file, 5006-r-fill-23e-completed.pdf.

The FDF files are almost (but not quite) text files, which makes them diffable. You can use this to quickly compare the effects of different changes without eyeballing through the PDF forms.

Web service

There's also an interactive Web server executable named serve-canadian-taxes. Launch the executable, visit http://localhost:3000 in your browser, and follow the instructions.

Installation

As you can deduce from the above instructions, you'll need to install the free pdftk executable to deal with PDF <-> FDF conversion. See their instructions. On Ubuntu you can simply run

sudo apt install pdftk

while on Fedora the invocation is

sudo dnf install pdftk-java

To install the complete-canadian-taxes executable, you'll need Haskell development tools. The simplest procedure overall is to install ghcup, then use it to install ghc (version 9.4 or greater) and cabal, then to run

cabal install canadian-income-tax

Library documentation

This is an open-source project licensed under GPL-3, and it comes with a library for easier reuse. The rendered library documentation is available at Hackage.