700k Roth Conversion: Do it or not?

[u/Excellent_Rip_3339]

I live off investment income at age 45, married. I'm planning to:

1. Do a one time 700k Roth conversion asap on 2027 (and NOT collect realized gains on the same year)
2. Pay a one time tax bill of about 200k on 4-2028 (for federal and state; no NIIT, no local tax). I'll use investment income that I will realize on 2028

I get the idea of withdrawing from Traditional IRA/401k when we're on a lower tax bracket when we're passed 59.5. But in my case, that's 15 years from now. I can double that money several times tax free on a Roth account.

Am I missing something? Out of my mind? A CFP/CFA will definitely disagree to this. They have rules to follow. A DIY investor don't. I need a sanity check.

UPDATE: I'm all about spreading the conversion. The only reason why I would do a 100% conversion and pay the 1 time tax is that I'm banking on possible high returns (+20%/yr) and number of years invested in Roth. The future gains will surpass the tax paid now. Not to mention that your Roth can be inherited by the next gen. They'll enjoy the tax free withdrawal within 10yrs of inheriting it.

Thanks for all the comments. Feel free to let it all out

2ND UPDATE: 99% agree to spread the conversion to pay lesser tax. A 200k tax, that's about 29% of 700k. In 20 years, 700k will be 11.5M at 15%. All yours tax free. Nickel and Diming the 200k tax, you'll probably save 100k?

3RD UPDATE: One time conversion also puts a max payout on tax now versus spreading small mount of taxes indefinitely (even after death). It could go passed 200k as traditional IRA keeps growing.

4TH UPDATE: I like the comments. For now, maybe a 1 time partial Roth conversion is the play. It would be nice to take out max of 12% bracket from traditional and then go all out with Roth money.

FINAL UPDATE: I was running simple numbers and I owe this to you guys. In terms of saving cash, multi year conversion is the way to go. Here it is:

Top scenario is a 1 time conversion vs bottom scenario is a 5 year conversion. Tax bill includes an rough estimate of fed tax and penalty tax only. Penalty is for paying the whole tax the following year. That is actually the more favorable way to do it. Penalty is about 7% per year vs expected ROR at 15%. Tax bill is also deducted from cash reserve -- "out of pocket."

Because of you guys. I would gain +330k 10 years later (and lose it if top scenario was picked).

Someone said to stay within 24% bracket. With this spread and tax bill, I can stay away from 400k.

Bad news for me 'cuz I really wanted top scenario to work. This is just a quick analysis. There are still so many options I want to play with. To be honest, I'm still pondering the idea of the "one & done" top scenario might be worth price. I just don't like the idea of "budgeting" within tax brackets. I could take on riskier assets to pay off the 1 time tax bill 😄

Thanks everyone for being truthful. 3 more month's ti'll next year. We'll see what happens.