I have a very, very high deductible, and an HSA. So the rule for me is stuff the max allowed into the HSA and spend that, since it is pre-tax money. Some things are clearly allowed for HSA, but not so clearly "deductible". Seems to depend on the employer (CIGNA has a good page on their site that is up to date - for those who remember that I complain about
my ins. co., it is not CIGNA, they just have a good site).
However, if it were a year you were planning some major surgery, and would blow out the IRS limits, don't use the HSA, deduct it all to get over the minimums. Some real complicated choices to make. My choice is to pay out of pocket up front, then wait to the end of the year. If I blew the numbers, leave it out of pocket. If not, do a summary of expenses and do a single withdrawal from the HSA for the total.
The big change this year was the removal of over-the-counter medicines from the deductible list, UNLESS you have a prescription. I ask the doc to write a prescription for everything, even aspirin.
I'm not a tax guy, and my advisor can find something wrong with what I did every year