Originally Posted by arbalist1

I calculated two scenarios. The first was calculating exactly what percent personal contribution I would need to get $23k in the Feb 20 paycheck. Then I did it without any personal contribution. Then ran the calculations for taxes of each paycheck.

The difference was just under $5,200 in tax withholding. I'd rather front load my 401k, and take the tax withholding. At least that way I have an extra $5200 sitting in the market instead of a tax free loan to the government. However you decide to do it though, the taxes all the up the same at the end of the year.