Question: What Happens If I Don't Use All My HSA Contributions Before the End of the Year?
Answer: Don't worry --
HSAs are
NOT like
FSAs in this regard. Any amounts you contribute to your HSA are yours, and carry over from year to year. If you don't use the money this year, it'll be available to you in the future if you need it.
So don't try to use up your HSA funds -- save them! In addition to providing you with tax-free savings for medical needs which may arise, once you turn 65, you can use any amounts remaining in your HSA for any reason -- medical or non-medical without penalty.