@Opus 17
<<"But this taxpayer has $100,000 sitting in the bank, and you can still only do the backdoor at $6000 or $7000 per year, correct?">>
That is correct, a taxpayer's new contributions to a Roth or Traditional IRA are limited to $6000 per annum ($7000 if over 50). So the OP can only move his $100,000 into an IRA at a rate of $6000 (or $7000) per annum.
But there is no income or contribution limit on the amount of money a taxpayer can convert from a Traditional to a Roth IRA, which is how a Backdoor Roth is done. The curve ball is that there will be a tax bill on any pre-tax money sitting in any or all of the taxpayer's existing traditional IRA's, thanks to the IRS's pro-rata rule. The pro-rata rule can be a bit confusing. Scroll down to The pro-rata rule in this web reference to see an explanation:
https://www.nerdwallet.com/blog/investing/backdoor-roth-ira-high-income-how-to-guide
Of course the pro-rata rule only becomes a problem if the taxpayer already has money in Traditional IRA's.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
