You can contribute another $1,000 (each spouse that is age 55 or older and covered under a HDHP) until you are enrolled in Medicare.
Check with your tax advisor or use a recent paystub to determine your current state tax rate.
* Not all states offer tax benefits on HSA contributions. Consult your state department of revenue for information on your state's tax treatment of HSA contributions.
** This is an estimate and not a representation of the exact future value of your HSA