Does asset custodian matter when determining which capital gains lot you sold? (USA)

External question — Personal Finance Stack Exchange Author: tsj Original post: https://money.stackexchange.com/questions/150415 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Say you bought N shares of some company at broker X on Jan 1, 2021. You bought N more shares of the same company at broker Y on Feb 1, 2021. Then on March 1, 2021, you sell N shares with broker Y . For reporting capital gains, assuming a FIFO strategy, do you consume the Jan 1 lot or the Feb 1 lot? I can imagine it might be the Jan 1 lot if you treat all shares owned by you to be indistinguishable, existing in an abstract, broker-agnostic pool. I can imagine it might be the Feb 1 lot if you say the shares are distinguishable if they are held by different parties (brokers), i.e. you couldn't have sold with Y the Jan 1 lot bought with X without first transferring it to Y . This situation is probably more likely to come up with crypto than with stocks -- I think the question is identical in either case.