<prompt> Human: Back in April, I found out that I was eligible for a special scenario. When I did Open Enrollment at my job in October of 2016, I technically opened an HSA account, even though I did not contribute to it. When I had my taxes done, I asked my CPA whether I could fund it for 2016, and because I was on a HDHP, I was able to fund the account. To do this, I linked my Chase account to my Fidelity account and transferred the funds. I noted that I saved quite a bit on my recalculated taxes by essentially paying myself.Currently, I have an election to contribute money pre-tax to my HSA. But in the future, if I chose to fund this HSA with post-tax funds just max it out January 1 to allow the money to have the most time in the market, would it be any different than pre-tax? Would I lose out on either end? Is it any different come tax time?  <response>: By making the contributions pre-tax instead of post-tax you and your employer, to a greater extent avoid having to pay payroll taxes on that money. So the best way to fund a HSA is with pretax contributions out of your paycheck. 