14 CFR § 61.19 - Duration of pilot and instructor certificates and privileges.
(1) The holder of a certificate with an expiration date may not, after that date, exercise the privileges of that certificate.
(2) Except for a certificate issued with an expiration date, a pilot certificate is valid unless it is surrendered, suspended, or revoked.
(b) Paper student pilot certificate. A student pilot certificate issued under this part prior to April 1, 2016 expires:
(1) For student pilots who have not reached their 40th birthday, 60 calendar months after the month of the date of examination shown on the medical certificate.
(2) For student pilots who have reached their 40th birthday, 24 calendar months after the month of the date of examination shown on the medical certificate.
(c) Pilot certificates.
(1) A pilot certificate (including a student pilot certificate issued after April 1, 2016 issued under this part is issued without a specific expiration date.
(2) The holder of a pilot certificate issued on the basis of a foreign pilot license may exercise the privileges of that certificate only while that person's foreign pilot license is effective.
(d) Flight instructor certificate. Except as specified in § 61.197(b), a flight instructor certificate expires 24 calendar months from the month in which it was issued, renewed, or reinstated, as appropriate.
(e) Ground instructor certificate. A ground instructor certificate is issued without a specific expiration date.
(f) Return of certificates. The holder of any airman certificate that is issued under this part, and that has been suspended or revoked, must return that certificate to the FAA when requested to do so by the Administrator.
(g) Duration of pilot certificates. Except for a temporary certificate issued under § 61.17 or a student pilot certificate issued under paragraph (b) of this section, the holder of a paper pilot certificate issued under this part may not exercise the privileges of that certificate after March 31, 2010.