The Unrealized Capital Gains tax debate makes me think about charitable giving. Should one give away more in a year when one has higher unrealized capital gains? If you aim to donate a percentage of income, as with Christians who tithe should you include cap gains and losses?
I really don't know, so I'd be interested in answers. This is the kind of practical question Protestant theologians ignore completely, Roman Catholics used to think about but probably not the past 200 years, and Orthodox Jews are really good at. References?
Two things I'm pretty sure of are: (a) Don't donate capital gains when liquidity constrained. An old lady need not take out a mortgage to donate when her house price rises (b) Don't spend resources on transaction costs, e.g., finding the market value your business each month.
It does seem to me that capital losses should not result in zero donations (or filching from the collection plate). Donating is good for your soul, even if your income was negative.
Just having to ask this question shows why Christians should not tithe strictly. It is legalistic, and if there really is a moral command to give 10%, then we must figure out what "income" means, and the best answer is that changes in wealth should count.
John Wesley had an income of 30 pounds a year. He lived in 28, and gave away 2. The next year he received 60 pounds and gave away 32. The third year he received 90 and gave 62. The fourth he received 120 and gave away 92. So goes the story.
See note 113 of http://media.sabda.org/alkitab-6/wh3-ref/jt-tlow.pdf, to Jackson's "C. Wesley," i., 25. It sound false literally to me, but true in spirit. It would be useful for someone to track it down. Wesley *was* very rich, and seems to have given away over 90% of his income.