The I-751 form is used to break a conditional residency. When one marries a U.S. Citizen and they have been married for less than two years, you receive a conditional residency. This residency is for two years. An I-751 is used to change the two year card to a ten year card. There are many issues that can arise with the I-751.
Here are some common issues:
One issue is whether or not the alien spouse and child have to file separate forms. There are times that the spouse received his or her conditional residency at a time different than his or her child. The general rule is if the child received their conditional over 90 days later, the child must file a separate I-751.
Another issue is if there is a divorce, can one file an I-751 immediately or have to wait until the 90 days before the expiration date? The general rule is that you can file immediately when the divorce is finalized. You will need to seek a waiver of the joint requirement.
Another common issue is when the conditional residency is expired and you have a pending I-751 petition, can you travel? The general rule is yes. It is sufficient to have your expired green card with the receipt of the I-751. You can also get your passport stamped as a permanent resident at the local immigration office.