HSAs do not have a deadline to use your funds, so you are able to rollover your balance at the end of your benefit plan year as long as you are still covered by a high deductible insurance plan. There is no deadline to submit your receipts for reimbursement.
You are also able to contribute to your HSA for the current tax year up until April 15th of the following year. Meaning, for your 2021 taxes, you can contribute to your HSA up until April 15th, 2022.