A grace period is a timeframe in the new plan year during which you can incur new expenses and file claims. This timeframe, established by your employer, is up to 2½ months after the end of the plan year. If your plan year ends on December 31, and your plan offers a grace period, you have until March 15 to incur new expenses and use money left in your Healthcare FSA to pay them.
To confirm if your plan offers a run-out log into your online account. To see your plan filing dates hover your cursor over the i (information) icon next to the plan name.