Tl;dr, my question is whether setting up an automatic ACH transfer directly from one HSA I own to another would cause any problems.

Hey all, I'm trying to optimize my efficiency with investing in my HSAs. My employer's HSA receives employer contributions and payroll deductions from my wages, neither of which can be routed to an outside institution's HSA. This employer HSA, however, cannot be invested. So...

I'm leaving my employer HSA open and making payroll deduction contributions to it to avoid FICA taxes. I want to transfer these funds to my Fidelity HSA fairly quickly so I can invest in long-term growth.

In Fidelity's site I have two main options to get funds from my employer HSA into the Fidelity one; I can issue a transfer of assets request, which takes a lot of time and cannot be automated, but is specifically mentioned as being 'okay' in the eyes of the IRS. The other option would be, of course, an ACH transfer, which I'd be able to automate, but I couldn't find anything online confirming or denying whether this is acceptable.

Do you know whether or not this would work, and if there would be any issues?