“A friend of mine was born in the U.S. in 1964 and went home to Ireland when she was about seven years old. She became a nurse and returned to work in the U.S. for a couple of years before going home and getting married. She now has five children, ranging in age from 10 to 18 years of age. 

“She'd like to register them as U.S. citizens, but the older ones are now past the deadline (she thinks) for claiming citizenship through her. Is it true that they can claim citizenship through my friend’s father? He emigrated in the late 1950s and became a U.S. citizen after serving in the army. He worked here for many years and returned to live in Ireland in 1970.  How should she proceed with obtaining citizenship for her children?”

From the information you’ve provided, it seems like the kids are in luck. They automatically acquired U.S. citizenship through their mother at birth. 

The guidelines for passage of citizenship from parent to child are very clear.  They also depend on when the child was born.

In your friend’s case, a child born outside the U.S. after November 1986 to one citizen parent acquires U.S. citizenship at birth provided that the qualified parent resided here for five years – two of these years must have occurred after the parent was 14. 

So the fact that your friend came back here to nurse prior to getting married is critical and will save her a great deal of time and energy that she would have had to expend if that wasn't the case. 

The kids would not be able to claim any immediate citizenship rights through your friend’s father. Only parents can pass citizenship to their foreign-born children. 

What your friend will have to do next is apply for a Consular Report of Birth Abroad at the Dublin Embassy (CRBA).  Of course she'll need plenty of paperwork – proof of her own U.S. citizenship (birth certificate), proof that she was married when her kids were born (the citizenship acquisition rules are different for children born out of wedlock), and evidence that she worked here for two years after she turned 14 (employment letter from hospital, tax returns, etc.).

Once the CRBA is approved the kids are officially citizens and can then apply for passports. That can be done at the embassy too.

Your friend’s oldest children haven't aged out of becoming citizens. There's no time limit on when a citizen child born abroad has to claim citizenship. The government prefers that foreign births are registered soon after they happen, but there's no law that mandates this.

Any foreign-born child with a parental citizenship connection should definitely investigate how citizenship is automatically acquired.  If the friend in this week’s question had married a U.S. citizen the five children would have also acquired citizenship at birth provided that one of the parents had resided in the U.S prior to the births. This would make it even easier to formalize citizenship because there’s no specified residence time, and no requirement of two years of residency after the parent turned 14.