If you should miss a deadline in filing for a benefit or appeal you can try to have the agency apply the doctrine of equitable tolling to the issue if there is evidence that missing the deadline was unavoidable in your particular case. For example, if you had a medical issue that stopped you from meeting a deadline (like a coma or a psychotic break or medication which rendered you unable to think clearly), or a non-medical issue which made you unavailable for meeting the deadline (for example incarceration, being shipwrecked, being kidnapped, being on jury duty,etc.). Equitable tolling of a deadline may be rendered in the interests of giving you equal access to the VA or a court or VBA.
http://www.supremecourt.gov/opinions/10pdf/09-1036.pdf
