This is a great way to bridge the gap to maximizing the 401K contribution limit of $61K (for 2022). I am a few weeks out from hitting 2nd year pay so I ran some numbers on this. Just like Boiler said, if you are making $305K, the IRS compensation limit for an employer to contribute to a 401K (the employee can still contribute), you’ll be in this scenario. Contributing 1.28% ($3,900) will be the missing difference to get you up to $61K. See attached snapshot.

An important note about “UPS/IPA MPP” fund, which is also called an ATTD-After Tax, Tax Deferred, is that even though it’s after-tax dollars, like a ROTH, the earnings are taxed, unlike a ROTH. Fortunately, our plan with Fidelity allows for in-service conversion. You can take contributions and earnings made to the ATTD and roll over into a traditional IRA, then convert into a ROTH IRA (similar to a back door ROTH). You will owe taxes on any earnings that occurred since the money was sitting in the ATTD. If you do this on a regular basis (at least once a year), the taxes won’t be that big of a deal. Google search “Mega Back Door ROTH” for more details.