Looking for a platform I can set up ACH auto payments with the current tenants.

We offer 4 different payment methods to our tenants: Online ACH via our PM software (no charge) Deposit @ our bank ($3 charge) Credit Card ($5 + cc fees) Mail ($10 charge)Notice we charge a fee for the less desirable options to encourage the behavior we want:)

As for payments, Zelle and paypal are good for personal accounts but if it is a business bank account he is using he can set up ACH or just give the tenant deposit slips to deposit the rent himself. 

Or can I request ACH deposits only.

Completely free of charge for both parties, funds show up instantly, and there is nearly no recourse for tenants to claw back money (like ACH) or issue a chargeback (like CC).

If they improve on it, $9/month for a rental with ACH option looks very reasonable

ACH or credit card. 

@Lucas Laufenberg Automated clearing house (ACH Payments)... you can set this up with your financial institution... like how tenants pay their utilities through their online banking... when they add a payee instead of utilities or a cell phone bill they will search for your corporation and deposit money directly into your account monthly... 

If you have gone through the permitting process in Denver, you know that brain ache is worth a couple grand.

@Mark DavidsonHere are considerations in choosing a Solo 401k provider and bank to provide the account:Solo 401k Bank Account Considerations:Here are some general considerations:If you want access to bank checks, a debit card and/or the ability to ACH funds out, you will need a bank, credit union etc. rather than a brokerage.There are 100s of banks and credit unions that have opened accounts for a Solo 401k.Keep in mind that the bank's role is limited to simply providing the account (i.e. no tax reporting, no recordkeeping, etc.) such you may wish to de-prioritize familiarity with Solo 401k plans and focus on other things that are important to you (i.e. branch locations, fees, etc.).If you want the ability to invest in stocks, mutual funds, etc., you will need a brokerage account.Many brokerage firms will open "free" accounts (i.e. no setup fee, no maintenance fee), which will also come with checkbook access and the ability to wire funds out such that they function as a "hybrid" between a bank and/or brokerage account.If you are looking for names of banks that open bank accounts for Solo 401k plans, there are many banks where we have received positive feedback including Wells Fargo, Bank of America, PNC along with local banks and credit unions just to name a few.