How about a single laid-off 50 YO NYC resident who inherited 1M shares of AGNC in a taxable account and has no other significant assets or liabilities and whose estimated living expenses (excluding taxes) are $200k/yr? FI or not? Obviously the lack of diversification is a huge red flag, but I would consider such a person to be FI even if his annual living expenses including income taxes is (likely) >4%.
That person could do what I do. Discount the AGNC investment by the taxes you'd expect to pay when liquidating by your plan. In other words, not dumping it all today (unless that's your plan), which might trigger as high as a 23.8% fed tax + state. Instead you'd be selling it over the years at 15% fed + 10% (?) NY state and city income tax.
So if your AGNC investment was worth $10M, and it had doubled since inheriting such that $5M is cap gains, you discount the investment by 25% of $5M, or $1.25M. So your $10M holding is really worth $8.75M after tax.
Supposing this is your only taxable income, you could figure the withdrawal % rate as your withdrawals/$8.75M and ignore the income tax as an expense, because you've already discounted the asset by the taxes you owe.
This isn't a very popular method here because taxes really are an expense, but as long as it works out, nobody else should care what you do.
The good part of this is that you don't skew your budget because of financial moves you make that really have nothing to do with your other living expenses or spending. Roth conversions are the golden case for this. I owe income tax on the amount I convert. But I'm not spending that money. I'm just moving it from one pocket to the other, while ridding myself of a deferred tax liability. I'm not going to cut back on my spending because the tax of doing conversions used up some of my budget. So I don't treat the tax due to a conversion as an expense, nor do I treat cap gains from the sale of an asset as an expense. They are deferred tax liabilities. Liabilities are subtracted from assets.
I'll probably get flak again for stating this, but I don't care. I've been managing my money this way for nearly 30 years when my employee stock options took off, and it has never caused me any problems or confusions about my financial state. Trying to do a budget or track my expenses to my planned WR with uneven taxes depending on when I exercised options, did Roth conversions and sold appreciated stock would have been a nightmare. So it's an easy decision for me to do it my way, which makes perfect sense to me, rather than adhere to someone else's standard which would be a mess for me.
For calculations on the amount of my estate, I remove the tax on appreciated assets (but not my tIRA) because of the stepped up basis heirs will get. So I have two sets of "books", but it all fits on one spreadsheet.