If you are a U.S. citizen or lawful permanent resident who intends to get married to a foreign-born person in an overseas location, there are a number of issues to plan around, such as:
We'll discuss all of these issues below. You might also want to consider getting a fiance (K-1) visa and having your wedding in the U.S. See Get Married Abroad or Bring Your Foreign Fiance To The U.S.?
Don't set a wedding date before knowing, for example, whether the country where you plan to marry in requires that you stay there for a minimum period of time first; or pack your bags before learning whether you need to obtain a particular type of visa or bring your birth certificate or other documents.
Also, find out whether the country's laws place any religious restrictions on your marriage, whether you will need to have a blood test, and so on. If you are planning on entering into a same-sex marriage, this is allowed in some, but not all countries. If it's legally valid in the country where you marry, it will work for U.S. immigration purposes.
To find out the exact requirement of the country of your intended marriage, your best resource is that country's embassy or consulate in the United States. The U.S. State Department's website provides contact information.
Consider hiring a company that specializes in organizing weddings abroad. A reputable one will be able to tell you how to satisfy the country's matrimonial and immigration requirements.
Contrary to popular misconception, marriage between a U.S. citizen or permanent resident and a foreign-born person does not automatically confer upon that person U.S. citizenship or other immigration status. You will have to file a good deal of paperwork first, and get through a lengthy application process before the foreign-born spouse can so much as set foot in the United States.
The first part of that application process is for the U.S.-based spouse to file what's called a petition, on Form I-130 (issued by U.S. Citizenship and Immigration Services, or USCIS). When the time comes for the U.S. citizen or resident to submit this form, they will need to include a copy of an official version of your wedding certificate.
The U.S. government keeps a close watch on what types of certificates are considered valid proof of a wedding in the various countries around the world. If, for example, you try to present a document from a ship's captain or a church, and those are not recognized for official purposes in the country where you were married, your I-130 petition will be denied. Go to the State Department website and, on its Reciprocity and Civil Documents by Country page, check on the accepted, valid sources for marriage certificates.
For more information on the application process to petition for a foreign-born person based on marriage, see How to Get a Foreign Family Member Into the U.S. as a Lawful Permanent Resident.
In order for the U.S. petitioner to succeed in sponsoring the immigrant, they will need to show sufficient financial resources to support the immigrant at or above 125% of the income levels set by the U.S. Poverty Guidelines (issued annually and available on the USCIS website). The petitioner will, as part of proving this, need to fill out an Affidavit of Support on USCIS Form I-864.
One of the requirements for filling out this form is that the sponsor reside in the United States or a U.S. territory or possession. If part of the reason that you are getting married outside of the U.S. is that the petitioner already lives overseas, you need to look closely at this requirement. At a minimum, the sponsor will have to return to the U.S. by the time the Form I-864 is submitted (which might happen in the middle of the process, by mail; or at the final visa interview at a U.S. embassy or consulate abroad).
Also, the sponsor will have to prove that they actually live in the United States. U.S. immigration authorities will want to see evidence of where the sponsor lives (perhaps in the form of an apartment lease or mortgage), where they're working, and so on.
If the sponsor doesn't yet have a job in the U.S., but is living there, that's not fatal. To prove sufficient financial resources, it might still be possible for the sponsor to find a friend to jointly submit a separate Form I-864, or a household member to submit a Form I-864a.
But asking someone to do this is major. It means that they take complete financial responsibility for the immigrant if the primary sponsor fails to do so. See Financial Support You'll Need to Apply For a Family-Based Green Card for more information.