8 CFR 312.5 – Failure to meet educational and literacy requirements
(a) An applicant for naturalization who fails the English literacy or history and government test at the first examination will be afforded a second opportunity to pass the test(s) within 90 days after the first examination during the pendency of the application.
(b) If an applicant who receives notice of the second scheduled examination date fails to appear without good cause for that second examination without prior notification to the Service, the applicant will be deemed to have failed this second examination. Before an applicant may request a postponement of the second examination to a date that is more than 90 days after the initial examination, the applicant must agree in writing to waive the requirement under section 336 of the Act that the Service must render a determination on the application within 120 days from the initial interview, and instead to permit the Service to render a decision within 120 days from the second interview.