That’s partly why Fidelity Charitable began accepting Bitcoin donations. Its donors were asking about it, and the fund saw an opportunity after the I.R.S. clarified the rules.

“We didn’t do anything until the I.R.S. determined that it was going to be treated as an asset,” said Matt Nash, Fidelity Charitable’s senior vice president of donor engagement. “If you look at an overall mix of a portfolio and one asset is gaining value much faster than another, then it’s strategic to donate that asset to charity. You’re getting better overall value for the dollar.”

Mr. Nash said that the fund did not accept Bitcoin directly and that it did not hold any cryptocurrencies in its own portfolio. The fund uses Coinbase, a digital asset exchange company, to accept donations and convert them into dollars as soon as they come in.

It’s a similar process with stocks. Fidelity Charitable turns assets it receives into cash right away, but it’s even more important that the fund transfers Bitcoins into dollars because of its volatility. Bitcoin fell by nearly 20 percent from Aug 28 to Sept. 11, for instance. Fidelity does not want to be caught holding something that can decline so quickly.

Easier to Track

Some technology entrepreneurs and cryptocurrency enthusiasts say that the system these currencies are built on can alter how people give and track their donations.

Cryptocurrencies use a blockchain, a digital ledger that records transactions. Normally, when someone pays cash for an item in a store, the transaction is seen by only the buyer and the seller. With a blockchain, the transaction is recorded in a digital ledger in near real time that anyone can see. It is also impossible for transaction details to be changed.