I'm not sure exactly what you mean by "tax harvest." If your wife sells an investment for a gain in her account, and you sell another investment for a loss in your joint account in the same year, and the two of you file a joint tax return (married filing jointly) for that year, the loss on the sale in your joint account will offset the gain on the sale in your wife's account. Essentially, on a joint tax return everything gets added together. It doesn't matter who had the gain or the loss, or that the gain and the loss were in different brokerage accounts.
