tastyworksTaxes

Automate the calculation of yearly taxes for a tastyworks export in the context of the German private asset management tax situation.

Validation Status and Disclaimer

This project is intended as an open-source tax preparation aid for private German investors using TastyTrade/Tastyworks transaction exports. It applies documented rules for FIFO matching, option trades, corporate actions, USD/EUR conversion, and selected German tax report categories, with regression tests covering the implemented behavior.

It is not a substitute for professional tax advice. Tax law, broker export formats, and individual circumstances vary; users should review generated figures against broker statements and consult a qualified tax advisor before filing.

❗ UPDATE (December 2024): The 20,000 EUR limit on offsetting losses from options trading has been abolished. The German Bundesrat approved this change on November 22, 2024 (Jahressteuergesetz 2024). Losses from derivatives can now be fully offset against capital gains, with retroactive application to all open cases. This follows the Federal Fiscal Court ruling that the previous restriction was unconstitutional.

Current Coverage:

• Stocks, options, selected corporate actions, dividends, interest, fees, and USD/EUR conversion are handled by the implemented calculation pipeline.
• Asset classification support is evolving. Equity ETF partial exemption is implemented; other fund classes are identified but may require manual review.
• Unsupported or ambiguous transaction patterns are intentionally surfaced as errors or warnings rather than silently estimated.

Stocks:

• Gains and losses are calculated using the FIFO (first-in, first-out) method.
• Transaction costs are fully deductible when incurred.
• Other account and deposit fees are already covered under the flat rate operating expenses deduction.
• Dividends from certain German companies like Vonovia, Deutsche Telekom, Freenet are tax-free.
• Losses can only be offset against gains from stocks in the same year. Remaining losses are carried forward indefinitely.

Options:

• Each option trade is settled individually, no combined calculation for complex strategies.
• For writing (selling) options, gains/losses are calculated when the position is closed, either by buying back the option or through expiration/assignment.
• For buying options, gains/losses are calculated similar to stocks based on sale proceeds less purchase costs using the FIFO method.
• The FIFO method is used to match opening and closing transactions for accurate profit/loss calculation.

Installation & Setup

Dependencies Installation

Before running the project, ensure all dependencies are installed. Execute the following command:

pip install -r requirements.txt

Downloading Data from Tastyworks

IMPORTANT: You MUST download "Transactions" history, NOT "Orders" or "Activity" data.

1. Go to https://my.tastytrade.com/app.html#/trading/activity
2. Click on "Transactions" tab (NOT "Orders" or "Activity")
3. Set the date filter to your desired range
4. Set to show only "filled" trades
5. Click the export button to download the CSV file

⚠️ Important Notes:

• Export limit is 1000 rows per file
• Only the new TastyTrade format (21 columns, ISO 8601 dates) is supported
• The old TastyWorks format is no longer supported (as of November 2024)
• If you have more than 1000 transactions, download multiple files with different date ranges and merge them (see below)

Usage

After installing the dependencies, you can run the main program using:

python -m tastyworksTaxes.main [--write-closed-trades <output-file.csv>] <tastyworks-data.csv>

Example with test data (2018-2025):

python -m tastyworksTaxes.main test/transactions_2018_to_2025.csv

Merging Multiple CSV Files

If you have multiple export files from Tastyworks due to the 1000 row limit, you can merge them using Python:

import pandas as pd

# Read all CSV files
df1 = pd.read_csv('file1.csv')
df2 = pd.read_csv('file2.csv')
df3 = pd.read_csv('file3.csv')

# Concatenate and remove duplicates (keep all if no duplicates)
merged = pd.concat([df1, df2, df3], ignore_index=True)
merged = merged.drop_duplicates()

# Sort by date (oldest first)
merged = merged.sort_values('Date', ascending=False)
merged.to_csv('merged.csv', index=False)

Or use simple shell commands if files don't overlap:

# If date ranges don't overlap, simple concatenation works
(head -1 file1.csv && tail -n +2 file1.csv && tail -n +2 file2.csv && tail -n +2 file3.csv) > merged.csv

Test-Driven Development

The project uses pytest for test-driven development. To run tests, use:

pytest test/

For verbose debugging output, use:

python -m pytest test -s --log-cli-level=DEBUG

Recent Improvements

• Split Handling Fixed: Reverse splits now correctly handle short positions (ceiling rounding), scale cost basis to maintain per-share cost, and preserve basis for zero-quantity lots
• Corporate Actions Fixed: Symbol Changes and Stock Mergers now preserve original cost basis instead of incorrectly realizing gains/losses
• Enhanced Partial Exemptions: Partial exemption (Teilfreistellung) calculation improved for equity ETFs (30%). Other fund types (Mixed, Real Estate) are correctly identified and generate warnings, but their specific exemption rates are not yet applied in the final tax summary
• Improved FIFO Processing: Refactored to forward-chronological processing for more accurate trade matching

Known Limitations

The following areas are intentionally documented so users can decide whether the generated output is complete for their filing situation.

Unimplemented Tax Requirements:

• ETF advance tax payment ("Vorabpauschale") is not implemented. This is yearly fictitious taxable income on accumulating ETFs (70% of base interest rate × fund value at start of year, minus distributions). Required by German tax law since 2018.
• Short selling stocks beyond annual limits: 30% substitute assessment base (§ 43a Absatz 2 Satz 7 EStG) is not implemented.

Corporate Actions:

• While Symbol Changes and Stock Mergers are now handled correctly, Reverse Splits with unrecognized description formats may be incorrectly processed as taxable trades. These events should be manually verified.

Other Limitations:

• Fee treatment should be reviewed against the applicable tax form instructions and broker statements.
• Partial exemption rates are currently applied for equity ETFs; other fund types need manual handling in the final tax review.

Contributing

Contributions are welcome, this software was a lot of work. Try opening an issue or better a pull request.

License

This software is under the MIT License.