- Roth降低retirement AGI。AGI defines other tax and other costs (Medicare premium...)
- Roth 401K，如果公司offer，好于Roth IRA：higter contribution amount, no income limitation
- Roth 401K actually can contribute more more than regular 401K. (Same amount valued more on retirement withdrawal time).同样放满，Roth其实是多放了tax那部分。
- Uitill 2025,the marginal tax rate is historically low. If can stay within same tax bucket, could consider converting IRA to Roth IRA.
- Rollover to Roth IRA tax free. (10 reasons to buy Roth before tax deadline https://www.forbes.com/sites/financialfinesse/2020/07/13/why-you-might-want-to-contribute-to-a-roth-ira-by-july-15th/#405b8bc75611 )
- All Roths: after 5 years, withdrawn original investment amount penalty free.
- Roth IRA only: No RMDs after age 72.
退休以后还要注意每年的MAGI。如果高了，许多tax credits 不适用于高AGI。Medicare premium 会随着AGI的升高而增加。
PS
form 8606 backdoor Roth 算法：rollover $2，after tax contribution $2， (Assuming no gains)
- convert to Roth $2: $1 towards income base, $1 免税，$1 after tax base carry over, IRA = $2, Roth IRA = $2
- convert to Roth $4: $2 towards income base, $2 免税，$0 after tax base carry over, IRA = $0, Roth IRA = $4
