I have a current FSA for medical and dependent care reimbursements. How will this impact my ability to join the HSA/HDHP plan?

You will need to spend all your FSA money by December 31, 2018 in order to contribute and have contributions made to your HSA account. While you can still enroll in a limited purpose FSA if you are participating in the HDHP/HSA, the limited purpose FSA is for vision and dental expenses only. You will still be able to have a dependent care reimbursement account.