You may only apply for asylum if you are arriving in or already physically present in the United States. To apply for asylum in the United States, you may ask for asylum at a port-of-entry (airport, seaport, or border crossing), or, if you are already in the United States, you may file Form I-589, Application for Asylum and for Withholding of Removal, at the appropriate Service Center. You may apply for asylum regardless of your immigration status, whether you are here legally or illegally.
You must apply for asylum within one year of your last arrival in the United States, unless you can demonstrate that there are changed circumstances that materially affect your eligibility for asylum or extraordinary circumstances directly related to your failure to file within one year. You must apply for asylum within a reasonable time given the circumstances. Changed or extraordinary circumstances may include certain changes in the conditions in your country, changes in your own circumstances, and other events. For a non-exhaustive list of circumstances that may be considered changed or extraordinary circumstances, see 8 CFR § 208.4. See also, "Bars to Applying for and Receiving Asylum" in the links below.
You will be barred from applying for asylum if you previously applied for asylum and were denied by the Immigration Judge or Board of Immigration Appeals, unless you demonstrate that there are changed circumstances which materially affect your eligibility for asylum. You will also be barred if you could be removed to a safe third country pursuant to a bilateral or multilateral agreement. Currently, the U.S. has a Safe Third Country agreement with only one country, Canada, and the agreement does not apply to individuals applying for asylum affirmatively.
For more information, see “Bars to Applying for and Receiving Asylum” and INA § 208(a)(2).