I own my business, only employee single member LLC. I would like to start a cash balance plan (CBP).

Does anyone have one and what do you think about it? Any recommendations for a custodian in terms of cost and flexibility of investment options?

I considered it.. allows for much more put away than any other vehicle.

The reason I passed is it all pre tax deferral.. I hope to be in the same tax bracket when I retire and I expect that rate to be higher when I retire than it is now.

There is also some drag from the actuarial cost that is needed yearly.

I work in this space, meaning administration for qualified plans.

CB plans do allow for much larger deductions, but unlike DC plans (401(k), SEP, etc...) the contribution is required for a minimum of 3-5 years. Assuming you're okay committing to that timeframe, CB plans can be a great tax deferral above and beyond the DC limit. Your deductible contribution will be tied your age/income.

You can either work through a financial advisor to custody/manage the account for you, or you can open an account directly with a custodian like Schwab, Fidelity, etc...

As mentioned, you'll need an actuarial firm to draft the documents, handle the annual actuarial valuation, etc... that's going to run you a couple grand a year.

One thought regarding filling up both the tax-deferred and post-tax buckets... you can combine a cash balance plan with a Mega Backdoor Roth... so you contribute X in pre-tax dollars to the CB plan and then Y in Roth dollars to the 401(k) (Y is capped at $70k this year).