14 CFR 61.39
(a) Except as provided in paragraphs (b) and (c) of this section, to be eligible for a practical test for a certificate or rating issued under this part, an applicant must:
(1) Pass the required knowledge test within the 24-calendar-month period preceding the month the applicant completes the practical test, if a knowledge test is required;
(2) Present the knowledge test report at the time of application for the practical test, if a knowledge test is required;
(3) Have satisfactorily accomplished the required training and obtained the aeronautical experience prescribed by this part for the certificate or rating sought;
(4) Hold at least a current third-class medical certificate, if a medical certificate is required;
(5) Meet the prescribed age requirement of this part for the issuance of the certificate or rating sought;
(6) Have an endorsement, if required by this part, in the applicant's logbook or training record that has been signed by an authorized instructor who certifies that the applicant:
(i) Has received and logged training time within two calendar months preceding the date of
application in preparation for the practical test;
(ii) Is prepared for the required practical test; and
(iii) Has demonstrated satisfactory knowledge of the subject areas in which the applicant was deficient on the airman knowledge test; and
(7) Have a completed and signed application form.
(b) for ATP
(c) foreign pilots
(d) If all increments of the practical test for a certificate or rating are not completed on one date, all remaining increments of the test must be satisfactorily completed not more than two calendar months after the date on which the applicant began the test.
(e) If all increments of the practical test for a certificate or a rating are not satisfactorily completed within two calendar months after the date on which the applicant began the test, the applicant must retake the entire practical test, including those increments satisfactorily completed.