Upgrade Petition when Petitioner Becomes U.S. Citizen
If you have applied for your relative's petition while you are a permanent resident, and later if you become a U.S. citizen, the petition can be upgraded for the relative's visa classification, without filing a new petition. Therefore, if you are eligible for U.S. citizenship, you should apply as soon as possible.

If you receive an approval for a family based preference petition in one category, but later if your petition is upgraded, you can still keep your old priority date or the beneficiary may even become an immediate relative, as appropriate. Once a priority date is established in one family based preference classification, it can be recovered if the same beneficiary gets approved in another family based preference classification. However, the priority date cannot be ported from family based preference classification to employment based preference classification or vice versa.

For example, if a lawful permanent resident files an F2A petition for his spouse, and then later becomes a U.S. citizen, the F2A approval can be converted into an immediate relative petition. This is one reason why an F2A petition should always be filed, even when the petitioner expects to naturalize shortly.

If you become a U.S. citizen after the I-130 petition is already approved, send a letter to the National Visa Center. Include the information about your relative (name, date of birth etc.), a copy of your naturalization certificate, and a copy of the petition approval notice. Once they receive it, they will upgrade the petition and send the beneficiary any additional forms and information that may be required.

Sample letter

If you become a U.S. citizen and your relative's petition has not yet been approved by USCIS, you should send a letter to the USCIS service center that issued you the receipt notice. Make sure to include the information about your relative (name, date of birth etc.), a copy of your naturalization certificate and a copy of your petition receipt notice.

Children
Children (unmarried, below 21) can immigrate along with the parent, if the parent's petition was filed by their permanent resident spouse. However, a U.S. citizen must file a separate petition for a spouse and for each child.

In other words, children were eligible to immigrate as derivative beneficiaries when the petitioning spouse was a permanent resident, but once the petitioning spouse becomes a U.S. citizen, they lost their derivative beneficiary status.

Therefore, if not already done so, as a U.S. citizen petitioner, you must file separate petitions for each child as long as the child is still unmarried, under age 21, and are your natural children or legal stepchildren (that is, the marriage took place before they turned 18), they qualify as immediate relatives just like the spouse.

Marriage:
If any child gets married and the petitioner becomes a U.S. citizen, as long as the petitioner is the child's natural parent or legal stepparent, it is possible to file a petition in F3 category.

Step Children:
If the petitioner is neither a natural parent nor a legal stepparent (marriage did not take place before the child turned 18), the child can not immigrate with the alien parent. In such situations, once the alien parent becomes a permanent resident, a new visa petition in the F3 category must be filed.

21+ Children:
If the child has turned 21 and no separate visa petition was filed for him/her, you (U.S. citizen petitioner) need to file a new, separate visa petition if you are the child's natural parent or legal stepparent. The child will be put in F1 category that is subject to annual quota and waiting list. While filing this new petition, it may be worthwhile to request USCIS to allow you to "recapture" the priority date. In other words, request them to assign an old priority date, the same priority date when the original I-130 visa petition was filed for the spouse. If USCIS assigns a new priority date, continue writing them letters.

Sample letter