[nybble41]

> Aren't brokerages required to file forms for every customer they serve?

They are, but there are corner cases where they might not have all the necessary information. For example, if you trade the same stocks or mutual funds through more than one broker then neither one will have enough information to determine the cost basis for each sale. It's also possible to move shares directly from one broker to another.

For crypto, in the US, none of the exchanges are currently required to track any of this to begin with (they aren't considered brokers) so it's up to the customer to keep track of the cost basis. Even if they did act as brokers the other issues still apply, plus the cost basis of your positions will be affected if you trade on your own without involving an exchange. For example, spending crypto on goods or services from an unhosted wallet can affect the cost basis of subsequent sell orders. The tax filings are probably simpler under the current system, since if exchanges were filing 1099-Bs you would need to submit adjustments to their cost basis reporting along with everything else.