**2019: 176k - 24k deduction = $152k taxable.**If you convert 80k, that brings your taxable income to $232. Let's apply 1/3rd of your basis ($4000) against that leaving you with $8000 basis for the next two years.

So $4000 of your conversion would not be taxed at all. The next 16k of the conversion would be taxed at 22% and the rest ($60k) is taxed at 24%.

**2020: 168k - 24k deduction = $144k taxable.**Let's convert $100k this year, bringing your taxable income to $244k. Apply another $4000 of your basis against this.

Again, $4000 of your conversion is not taxed. The next $24k would be taxed at 22% and the rest ($72k) taxed at 24%.

**2021: 174k - 24k deduction = $150 taxable.**Let's convert the remaining $91k to Roth and apply the remaining $4000 basis against this.

Again, $4000 of the conversion is not taxed. The next $18k is taxed at 22% and the rest ($69k) is taxed at 24%

Let's do a comparison to doing all this in one year.

**2019: 176k - 24k deduction = $152k taxable.**. Converting $271k brings your taxable income to $423k. Applying your entire $12k basis against that gives a taxable income of $411k.

Again, about $12k of the conversion will not be taxed. The next $16k would be taxed at 22%. The next $153k would be taxed at 24% and the remaining $90k would be taxed at 32%.

I've done all this in a hurry and I took lots of liberties (lots of rounding, using the same deduction and the same tax bracket limits each year, using the exact same basis each year) and I probably made a mistake or two (in other words, you should do all this again yourself). But I think it clearly shows that you pay higher taxes if you do all this in one year.

This example should also give you an idea of how the basis is applied against the total IRA over the 3 years. (Do not expect $4k each year. The number will vary but the 3 years will add up to your full $12k.)