loss harvesting question - multiple accts

[EliteZags]

say I own 1000 shares of a stock in Webull with $12 cost basis
and also 1000 shares in Vanguard with $16 cost basis

stock is currently at $12, if I sell 100 shares from Vanguard do I get to harvest the full $400 loss from that cost basis?
(and alternatively would selling 100 shares from Webull just be break even?)

[secondcor521]

say I own 1000 shares of a stock in Webull with $12 cost basis
and also 1000 shares in Vanguard with $16 cost basis

stock is currently at $12, if I sell 100 shares from Vanguard do I get to harvest the full $400 loss from that cost basis?
(and alternatively would selling 100 shares from Webull just be break even?)

Assuming both sets of shares are in taxable accounts and you don't purchase any more shares of the stock in any of your accounts (including dividend reinvestments, if applicable) within the wash sale window (~30 days before and ~30 days after the sale), then yes, that's how it works.

[phildonnia]

So, I guess what you're asking is whether you should use some kind of average cost for your basis, or maybe FIFO.

No, you wouldn't.   The shares are "identified" as being the ones you bought at a particular broker. 

If you own multiple lots with different costs within one account, then this would be more complicated.  As you've described it, your assumptions are correct: you're selling the same shares you bought at that broker.

However, keep in mind that the Wash Sale Rule applies to all your shares, wherever you hold them.  So, other purchases within 30 days before or after will affect your ability to harvest the loss.