pycgt

A capital gain tax calculator for crypto traders or investors with configurable locale support. While originally designed for Australian tax returns, it supports any fiat currency through configuration.

Features

• Locale-aware calculations: Configure your local fiat currency (AUD, USD, etc.) for cost basis and reporting
• Flexible accounting: Supports both FILO (Last-In-First-Out) and FIFO (First-In-First-Out) position matching
• Exchange log transformation: Built-in transformer for Bitstamp, IndependentReserve, Nexo, Exdos Wallet, etherscan and solscan transaction logs, extensible for other types of logs
• Comprehensive fee handling: Crypto fees trigger disposal events; fiat fees treated as incidental losses
• Australian tax compliance: CGT discount for assets held >12 months, configurable fiscal year

Known Limitations

• Limited types of transformers support (Extending work or manual transformation required for unsupported logs)
• No automated market data fetching for missing exchange rates
• Limited to assets defined in config.toml:
  • Supported cryptos: BTC, ETH, LTC, NMC, BCH, LINK, USDT, NEXO, SOL, TRX, TON
  • Supported fiats: USD, AUD
  • Supported pairs: btcusd, btcaud, ltcusd, ltcbtc, nmcusd, ethusd, ethbtc, bchusd, linkusd, linkaud, audusd, and Kraken-style pairs (xethxxbt, xethzusd, etc.)

Configuration

All settings are in config.toml:

[locale]
fiat = "aud"           # Local fiat currency (aud, usd, etc.)
fy_start_month = 7     # Fiscal year start month (7 = July for Australian tax)

[options]
position_accounting = "filo"     # "filo" or "fifo"
sort_by_datetime_asc = true
precision_threshold = 0.00000001

[data]
cryptos = ["btc", "ltc", "nmc", "eth", "bch", "link", "usdt", "nexo", "sol", "trx", "ton"]
fiats = ["usd", "aud"]
operations = ["buy", "sell", "deposit", "withdrawal", "gain", "loss"]
# ... see config.toml for full configuration

Important: The locale.fiat setting determines which currency is used for all cost basis calculations and tax reporting.

Trading Logs pycgt Can Process

pycgt expects CSV files with specific columns.

Some predefined columns are [data.fields] in config.toml:

Required columns:

• Datetime: When the trade happened (multiple formats supported)
• Operation: 'Buy', 'Sell', 'Deposit', 'Withdrawal', or 'Loss'

Optional columns:

• Type: Transaction type description
• Exchange: The exchange where the trade was made
• Pair: Trading pair (e.g., btcusd, btcaud, ethusd)
• Crypto amounts: BTC, LTC, NMC, ETH, BCH, LINK
• Fiat amounts: USD, AUD
• Fee columns: Fee(BTC), Fee(LTC), Fee(NMC), Fee(ETH), Fee(BCH), Fee(LINK), Fee(USD), Fee(AUD)
• Exchange rates: BTCUSD, BTCAUD, LTCUSD, LTCBTC, NMCUSD, ETHUSD, ETHBTC, BCHUSD, LINKUSD, LINKAUD, AUDUSD
• Comments: Any notes about the transaction

Other columns would be built according to CRYPTOS and FIATS configuration

CSV example (see example.csv):

Type,Exchange,Datetime,Operation,Pair,BTC,LTC,NMC,ETH,BCH,LINK,USD,AUD,Fee(BTC),Fee(LTC),Fee(NMC),Fee(ETH),Fee(BCH),Fee(LINK),Fee(USD),Fee(AUD),BTCAUD,BTCUSD,LTCUSD,LTCBTC,NMCUSD,ETHUSD,ETHBTC,BCHUSD,LINKUSD,LINKAUD,AUDUSD,Comments
Market,Coinbase,"2024-03-14T09:11:00.711Z",Buy,BTCAUD,1,,,,,,,,108524.67,,,,,,,108.52467,108633.19467,,,,,,,,,,,
Market,Coinbase,"2025-06-30T13:40:11.735Z",Sell,BTCAUD,0.998,,,,,,,162387.8306,,,,,,,,162.87646,162713.15,,,,,,,,,,,,

How to Run

Python 3 is required. Using virtualenv is recommended.

1. Prepare Python Environment

python3 -m venv .virtualenv       # Create virtualenv
source .virtualenv/bin/activate   # Activate virtualenv
pip install --upgrade pip         # Upgrade pip
pip install -r requirements.txt   # Install dependencies

2. Generate CGT Reports (Default Mode)

Process pycgt-formatted CSV files:

python main.py [csv_files...]

Example:

python main.py example.csv
python main.py file1.csv file2.csv  # Multiple files supported

3. Transform Exchange Logs (Transform Mode)

Convert exchange exports to pycgt format:

python main.py -t -x EXCHANGE [-o OUTPUT] INPUT_FILES...

Example:

# Transform Bitstamp export
python main.py -t -x bitstamp Bitstamp-Export.csv

# Custom output filename
python main.py -t -x bitstamp -o converted.csv Bitstamp-Export.csv

Supported exchanges: bitstamp

Example Output

When processing example.csv with fiat = "aud" in config.toml:

gain_or_loss,datetime,aud,discountable,description,buy_transaction.aud,buy_transaction.volume,...
loss,2024-09-07 09:11:00.711000+00:00,-27.46,N/A,,108524.67,1.0,2024-03-14 09:11:00.711000+00:00,...
gain,2025-03-15 09:11:00.711000+00:00,24.65,Yes,,108524.67,1.0,2024-03-14 09:11:00.711000+00:00,...
gain,2025-06-30 13:40:11.735000+00:00,54080.54,Yes,,108524.67,1.0,2024-03-14 09:11:00.711000+00:00,...
========================================================
Tax return report for year: 2024
Gross gains of the year: $0.00 AUD
Taxable gains of the year: $0.00 AUD
Net gains of the year:  $0.00 AUD
Portfolio of the year:
  btc: 1.0
  ltc: 0
  nmc: 0
  eth: 0
  bch: 0
  link: 0
========================================================

========================================================
Tax return report for year: 2025
Gross gains of the year: $54159.43 AUD
Discountable gains of the year: $54159.43 AUD
Taxable gains of the year: $27079.72 AUD
Net gains of the year:  $26753.82 AUD
Portfolio of the year:
  btc: 8.67e-19
  ltc: 0
  ...
========================================================

Note: The currency label (AUD) in the output adapts based on the locale.fiat setting in config.toml. If you set fiat = "usd", all outputs will show USD instead.

Extending pycgt

Adding New Cryptocurrencies

To add support for a new cryptocurrency:

1. Update config.toml:

   [data]
   cryptos = ["btc", "ltc", "nmc", "eth", "bch", "link", "your_coin"]

2. Add trading pairs:

   [data.pair_split_map]
   your_coinusd = ["your_coin", "usd"]
   your_coinaud = ["your_coin", "aud"]

Adding Exchange Transformers

To add support for a new exchange:

1. Create transformer/your_exchange_transformer.py inheriting from BaseTransformer
2. Implement the transform() method to convert the exchange's CSV format
3. Register it in transformer/__init__.py:

   elif exchange_type == 'your_exchange':
       return YourExchangeTransformer(input_files, output_file)

See transformer/bitstamp_transformer.py for reference implementation.

License

Distributed under the GNU General Public License v3.0. See LICENSE for more information.

Contact

Rob Lao - viewpl(at)gmail(dot)com