I tried to Google it and have only found a sort of opposite situation of calculating when a person achieves their desired returns goal: "For example, if you want to receive a 20% return on your stock purchase, you should consider an after-tax return rate. With a 15% tax rate on capital gains, you can sell when your shares rise by 23%, which will earn you a 20% return on your investment plus 3%, 15% of your capital gain income."

I don't really comprehend the math variables here, why is 3% equal to 15% of the capital gains. And how can I do it in reverse to decide if the savings in taxes equals the loss in value in a down market. Basically, how much % of capital gains would a position need to have to offset LTCG taxes in a down market? Or does that just not happen?

I'm thinking it is not cost effective to refill my cash bucket during this tax year since I already did a rollover, IRA withdrawal, and what I hope was capital gains harvesting to the top of my 12% tax rate. I wonder how anyone refills their cash bucket after a few down years used it up?