I had an HSA through Optum Bank for January 2018-May 2018 through my previous employer. We both contributed so there was about $600 in there.
I enrolled in a high-deductible at my new employer for June 2018-December 2018 and their HSA (through Aetna), and didn't put anything in until after year-end when I made a 2018 contribution for $2500 by April 15th (partially funded now and will fund the rest March 15th).
I incurred expenses at the ER in June 2018 when I fell down the stairs. I owe about $1500 and want to use the 2018 contribution towards that. Is that allowed? I used up the $600 in the other account already.