If you are filing form I-130 to petition for permanent residency for your spouse, you need to show your relationship is bona fide, or genuine. Give yourself time to think about what documents you have that can be used to prove your relationship. Below is a list with some ideas, but it is not a comprehensive list. An attorney can talk in more detail to you about your particular relationship and the best evidence for your case.
USCIS gives a list in the instructions of evidence to provide, and this is the best starting place. Below is USCIS’s list, with my advice for preparing evidence:
Documentation showing joint ownership or property
If you and your spouse own property together, like a house, car, or boat, include a title or deed with that shows both of your names.
A lease showing joint tenancy of a common residence
Include a copy of your lease if it shows both names.
Documentation showing co-mingling of financial resources
While not required, many couples do share a checking or savings account, and this is a good way to show evidence of your relationship.
Birth certificate(s) of child(ren) born to you … and your spouse
This one is pretty straight-forward! Include birth certificates of any children you had together. Make sure both of your names are on the certificate(s).
Affidavits sworn to or affirmed by third parties having personal knowledge of the bona fides of the marital relationship
Ask family members and friends to write letters affirming your relationship. Writers should include their full name, how they know you, how they know about your marriage (e.g.: I know they are really in love, I attended their wedding, or I enjoy eating dinner with them, or we took a trip together last year). Letters should end with an oath, swearing that the information provided is accurate.
USCIS states that each affidavit should also include the writer’s full name, address, date/place of birth, relationship to the couple.
Normally, it is also beneficial for the couple to write similar affidavits explaining how they met and describing the the relationship.
Any other relevant documentation to establish that there is an ongoing marital union
Include 3-10 photographs showing you and your spouse together in different places, seasons, and with different people.
Print and include emails, text messages, cards, or other notes between the two of you that show your relationship
Include your tax return, if it shows both of your names.
Another idea is to dig up records from trips you’ve taken together. Find airline tickets, confirmation emails, or matching passport stamps. These can be organized and labeled to show you travelled together to the same places.
Still need more evidence? Be creative! Look for Facebook posts showing both of you, receipts for wedding rings, wedding announcements, and photos from your wedding. Find documents for insurance benefits that have both your names, or even copies of your state ID’s showing you have the same address.