Correct. Had you obtained the return of excess contribution before the end of 2017, you would have received a code 2 2017 Form 1099-SA and everything regarding the return of excess contribution it would have been taken care of on your 2017 tax return. You missed that by a few days, so it must be reported by the HSA custodian on a 2018 Form 1099-SA which must be reported on your 2018 tax return. You'll be reminded about this when you get the code 2 2018 Form 1099-SA next year; it will take only a minute or two to enter it.
