choose-donation-assets

README

Charitable Donation Calculator for Capital Gains Assets

This Golang program reads a portfolio of capital gains assets (stocks, bonds, ETFs, mutual funds, cryptocurrencies, and so on) and current prices as JSON from standard input and, given a desired charitable donation amount, calculates the assets you should donate to maximize capital gains tax savings. (Optionally, you can make it calculate the donation that will maximize capital losses.)

This program requires Go 1.18 or later.

Installation

Use go install thus:

go install github.com/johnmuirjr/choose-donation-assets

which will install the choose-donation-assets executable.

Use

Run choose-donation-assets --help to see a long explanation of the input and ouptut formats and a list of options.

Examples

Suppose you have this input.json file:

{
	"assetSharePrices": {
		"VTI": 100.22,
		"BND": 12.35
	},
	"lots": [
		{"assetName":"VTI", "date":"2019-01-02", "shares":13, "shareCost":50.55},
		{"assetName":"VTI", "date":"2019-02-02", "shares":11, "shareCost":55.55},
		{"assetName":"VTI", "date":"2019-03-02", "shares":9, "shareCost":120.22},
		{"assetName":"BND", "date":"2019-02-03", "shares":50, "shareCost":10.00}
	]
}

Here are some example program runs (using jq(1) for pretty printing).

For a donation amount of 100 (the currency is the same as the asset costs and prices):

% choose-donation-assets -donation 100 <input.json | jq -S .
{
  "assetSharePrices": {
    "BND": 12.35,
    "VTI": 100.22
  },
  "donation": [
    {
      "assetName": "BND",
      "date": "2019-02-03",
      "shareCost": 10,
      "shares": 8
    }
  ],
  "totalCapitalGains": 18.8,
  "totalValue": 98.8
}

For a donation of 200:

% choose-donation-assets -donation 200 <input.json | jq -S .
{
  "assetSharePrices": {
    "BND": 12.35,
    "VTI": 100.22
  },
  "donation": [
    {
      "assetName": "VTI",
      "date": "2019-01-02",
      "shareCost": 50.55,
      "shares": 1
    },
    {
      "assetName": "BND",
      "date": "2019-02-03",
      "shareCost": 10,
      "shares": 8
    }
  ],
  "totalCapitalGains": 68.47,
  "totalValue": 199.02
}

For a donation of 10, which the program cannot satisfy:

% choose-donation-assets -donation 10 <input.json | jq -S .
{
  "assetSharePrices": {
    "BND": 12.35,
    "VTI": 100.22
  },
  "donation": [],
  "totalCapitalGains": 0,
  "totalValue": 0
}