Thanks. I have been trying to figure this out but was not able to find any guidance. It seems when you change jobs or HD plans and they require to use their own bank/HSA administrator, the clock "resets" in terms of past medical bills so the only way is to keep your older HSA active (assume you can as long as you keep it funded) and keep funding it to pay older expenses. tax benefits will then be figured out as part of 1040.
