To me, a taxable distribution is the box 1 amount even it is contains a RMD (that is also taxable) and there is not a code G - that would not have any withholding.
I'm just going by what the IRS says:
Any taxable distribution paid to you is subject to mandatory withholding of 20%, even if you intend to roll the distribution over later. If the distribution is rolled over, and you want to defer tax on the entire taxable portion, you will have to add funds from other sources equal to the amount withheld. You can choose to have your 401(k) plan transfer a distribution directly to another eligible plan or to an IRA. Under this option, no taxes are withheld.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
