Querys a journal for lots, reduces them, & returns ledger-format lot reductions to sdout.

$ python TaxingLots.py 'filename' 'query'

filename  -- a ledger file, entries sorted by date
query     -- a ledger query for commodities to augment / reduce

Sample usage:

$ python TaxingLots.py sample.journal Assets:Crypto

should give you the same output as the "sample-output" file in this repository.

Globably, this program:

1. Reads a ledger journal 'filename' and a ledger 'query' (what commodity or commodities are you interested in?) as arguments, and returns matching posts using the python ledger bridge, which must be compiled with your version of ledger. Its output defaults to sdout, so it never modifies its imput files.

2. Creates a list "stack" of commodity lots with dates and cost basis. Currently it handles bitcoin (BTC), litecoin (LTC), and ether (ETH), reducing from the oldest lot of each commodity first (First In, First Out, FIFO).

3. Reads the ledger line by line, outputing to stout. A. If a line has commodity reductions matching the query, the lot sales are reduced agains holdings in the "stack" of lots for that particular commodity. B. The resulting ledger notation is inserted in the line (or lines when multiple lots are booked against) and printed to stdout. C. Output currently assumes USD as reference currency for all lot cost basis calculations, to keep the IRS happy.

Notes:

Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line. Ledger is written by John Wiegley, released under the BSD license, and is available at http://ledger-cli.org.

TaxingLots.py returns lot reductions using Ledger's syntax, assuming USD as the reference currency for taxation purposes. It does not check that the transactions are balanced, since Ledger already does that. It simply manages booking and reducing commodity/cryptocurrency lots, but leaves the user in control of the overall transaction structure.

The program requires a CSV file with exchange rates for all commodities. Modify the getrates() function according to your needs and your rates file.

The program also inserts Income:CapitalGains legs where necessary when reducing lots. This gives Ledger the CapitalGains explicitly, so when you run TaxingLot's output back through Ledger, you may have to manually adjust some transactions do to currency exchange rate losses and/or gains.

I keep my ledger file in the actual currencies or cryptocurrencies that I transact in. With this program, I can convert to USD to calculate and report capital gains/losses with a USD basis for each transaction. The program adds exchange rate price declarations to the output. The original currencies or commodities are reported in comments on the same line as the converted USD rate.

This is my first attempt at Python. Pull requests are welcome. However, I may be slow to respond as I'm learning python and busy with my family and my non-programming work.

Writen by Joel Swanson. Version 0.03. Copyright 2017. Licensed under the GNU General Public License (GPL) Version 3. Absolutely no warranty, this program provided 'as is'. See https://www.gnu.org/licenses/gpl.html.