You have 240 days
I am currently in this situation. For H visas, you have 240 days "grace", during which you are eligible to work (a) provided you submitted a timely application for renewal, and (b) if you hear within the 240 days that you have been denied, you are then no longer eligible to work.
See also the following reply to my post on the Britishexpats.com board:
If an employer has submitted a timely-filed application for extension of
H-1B status (or any of several other types of nonimmigrant status), the H-1B
employee is authorized to "continue employment with the same employer for a
period not to exceed 240 days beginning on the date of the expiration of the
authorized period of stay." Here is the regulatory authority, available
through
http://www.immigration.gov/graphics/lawsregs/8cfr.htm.
At 8 CFR section 274a.12(b), INS regulations state:
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(b) Aliens authorized for employment with a specific employer incident to
status. The following classes of nonimmigrant aliens are authorized to be
employed in the United States by the specific employer and subject to the
restrictions described in the section(s) of this chapter indicated as a
condition of their admission in, or subsequent change to, such
classification. An alien in one of these classes is not issued an
employment authorization document by the Service.
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At 8 CFR section 274a.12(b)(20), the 20th class is described as follows:
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(20) A nonimmigrant alien within the class of aliens described in paragraphs
(b)(2), (b)(5), (b)(8), (b)(9), (b)(10), (b)(11), (b)(12), (b)(13), (b)(14),
(b)(16), and (b)(19) of this section whose status has expired but who has
filed a timely application for an extension of such stay pursuant to
sections 214.2 or 214.6 of this chapter. These aliens are authorized to
continue employment with the same employer for a period not to exceed 240
days beginning on the date of the expiration of the authorized period of
stay. Such authorization shall be subject to any conditions and limitations
noted on the initial authorization. However, if the district director or
service center director adjudicates the application prior to the expiration
of this 240 days period and denies the application for extension of stay,
the employment authorization under this paragraph shall automatically
terminate upon notification of the denial decision.
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Here is a table summarizing the classes above:
(b)(2) A-3
(b)(5) E-1 and E-2
(b)(8) G-5
(b)(9) H-1, H-2A, H-2B, and H-3
(b)(10) I
(b)(11) J-1
(b)(12) L-1
(b)(13) O-1 and O-2
(b)(14) P-1, P-2, and P-3
(b)(16) R
(b)(19) TN