今天有读者问：「我的 H1B 和小孩的 H4 延期于今年六月初寄出（有效期到今年9/30）。H1B 因为 Premium Process 已经批准，但小孩的 H4 还在 Pending。因为他暑假有 Camp 计划，没有办法回国重新申请签证，但是今年底我们有去英国的旅行计划，根据网上现在的 Form I-539 处理时间（到 Feb 2017），预计到时他的 H4 延期还会是 Pending 状态。我的问题是如果今年11月带他去加拿大申请 H4 签证，会不会有被拒的风险？是不是必须得回中国重新办理签证？从9/30到11月份我们离境这段时间他会是属于 Overstay 吗？」
根据这位读者的描述，若他孩子的 H4 延期申请在9月30日 I-94 过期之后仍然未批复，此时离境延期申请会视为自动放弃，若 USCIS 拒绝他小孩的延期申请，9月30日之后即为逾期逗留（overstay）。逾期逗留不但签证自动失效，而且通常情况下必须回母国重新申请签证、不能去第三国申请，依据是 INA 222(g)。
(1) In the case of an alien who has been admitted on the basis of a nonimmigrant visa and remained in the United States beyond the period of stay authorized by the Attorney General, such visa shall be void beginning after the conclusion of such period of stay.
(2) An alien described in paragraph (1) shall be ineligible to be readmitted to the United States as a nonimmigrant, except-
(A) on the basis of a visa (other than the visa described in paragraph (1))* issued in a consular office located in the country of the alien's nationality (or, if there is no office in such country, in such other consular office as the Secretary of State shall specify); or
(B) where extraordinary circumstances are found by the Secretary of State to exist.
* 注：这个地方 USCIS 网页缺一个 closing parentheses，是我添加的。
22 CFR 41.101 - Place of application (b) 也明确说道：
Place of application for persons subject to INA 222(g). Notwithstanding the requirements of paragraph (a) of this section, an alien whose prior nonimmigrant visa has been voided pursuant to INA 222(g), who is applying for a new nonimmigrant visa, shall make application at a consular office which has jurisdiction in or for the country of the alien's nationality unless extraordinary circumstances have been determined to exist with respect to that alien as set forth in paragraph (c) of this section.
(c) Exceptions based on extraordinary circumstances.
(1) An alien physician serving in underserved areas of the United States under the provisions of INA 214(l) for whom an application for a waiver of the 2-year foreign residence requirement and/or a petition to accord H-1B status was filed prior to the end of the alien's authorized period of stay and was subsequently approved, but whose authorized stay expired during the adjudication of such application(s), shall make application in accordance with paragraph (a) of this section.
(2) Any other individual or group whose circumstances are determined to be extraordinary, in accordance with paragraph (d)(1) of this section, by the Deputy Assistant Secretary for Visa Services upon the favorable recommendation of an immigration or consular officer, shall make application in accordance with paragraph (a) of this section.
(3) An alien who has, or immediately prior to the alien's last entry into the United States had, a residence in a country other than the country of the alien's nationality shall apply at a consular office with jurisdiction in or for the country of residence.
(4) An alien who is a national and resident of a country in which there is no United States consular office shall apply at a consular office designated by the Deputy Assistant Secretary for Visa Services to accept immigrant visa applications from persons of that nationality.
(5) An alien who possesses more than one nationality and who has, or immediately prior to the alien's last entry into the United States had, a residence in one of the countries of the alien's nationality shall apply at a consular office in the country of such residence.