Dual US-UK National Children: Social Security Numbers and the US Tax Rules That Follow

Short answer

A child born in the UK to an American parent is often a US citizen from birth. For US tax purposes, the child's Social Security number is the key that unlocks the Child Tax Credit. For 2026 the credit is up to $2,200 per child under 17, and up to $1,700 of it can be paid as a refund. Without a valid SSN issued by the return due date, the full credit is not available. Since 2025, at least one parent claiming the credit must also have an SSN. Your child's citizenship and SSN are handled by the US Embassy and the Social Security Administration. Our role is the tax side.

Key points

• The child needs an SSN valid for employment, issued before the return's due date including extensions.
• From 2025 the parent claiming the credit also needs an SSN. On a joint return, at least one spouse must have one.
• Maximum Child Tax Credit for 2026: $2,200 per qualifying child under 17. Refundable portion: up to $1,700.
• If you claim the foreign earned income exclusion, you cannot receive the refundable portion.
• A child without an SSN may still qualify for the $500 credit for other dependents, using an ITIN.
• A US citizen child has their own US filing and FBAR obligations once their income or accounts are large enough.

Getting the SSN

A child born abroad to a US citizen parent usually gets a Consular Report of Birth Abroad first, and then an SSN. In the UK, applications go through the US Embassy in London and its Federal Benefits Unit, which is the official contact. TaxStone does not handle citizenship documents or SSN applications, but once the number is issued we can make sure every year that qualifies is claimed correctly.

The Child Tax Credit for parents living in the UK

The credit reduces US tax, and part of it can be paid out even when you owe nothing. That second point is what makes it valuable for many families abroad.

If you use foreign tax credits (Form 1116): UK income tax usually wipes out the US tax on a UK salary. The refundable part of the Child Tax Credit can then be paid to you, up to $1,700 per child for 2026. It is based on your earned income above $2,500. Many families in the UK claim it this way.

If you use the foreign earned income exclusion (Form 2555): you cannot claim the refundable portion at all. Families sometimes switch from the exclusion to foreign tax credits partly for this reason. Revoking the exclusion has a five-year consequence, though, so it needs proper modelling first.

The SSN deadline matters. If the number arrives after the return is due, that year's credit is lost. An amended return cannot fix it, and you cannot claim it later once the number is issued.

Past years. If you missed the credit in earlier years when the child already had an SSN, an amended return may recover it within the normal time limits. We check this when we take on a family's returns.

UK Child Benefit and the US return

UK Child Benefit is paid to the parent, and UK rules apply to it. The High Income Child Benefit Charge claws it back when the higher earner's income is between £60,000 and £80,000. How Child Benefit is treated on a US return depends on the treaty and your circumstances, so we review it as part of preparing the return, not with a blanket rule.

The child's own US obligations

A US citizen child is a US taxpayer. Most children have nothing to file, but watch for these:

• Investment income. Above a small threshold set each year, the child may need a return, and kiddie tax rules can tax the income at the parent's rate.
• Junior ISAs and children's savings accounts. These are foreign accounts. If the child's non-US accounts together go above $10,000 at any time in the year, an FBAR is due in the child's name. Funds held inside a Junior ISA can also be PFICs, which brings Form 8621.
• Gifts from grandparents. Large gifts from non-US relatives can trigger Form 3520 reporting once they pass the annual threshold.

What we can help with

We prepare US returns for families in the UK, claim the credits they are entitled to, and keep the children's reporting in order alongside the parents'. Please tell us about every source of income in the household, in both countries, so we can confirm the right approach. We work entirely by email, so you have a written record of each year's position.

Sources

• Internal Revenue Code section 24 (Child Tax Credit), as amended by the One Big Beautiful Bill Act 2025
• IRS, Rev. Proc. 2025-32 (2026 Child Tax Credit and refundable amount)
• IRS Publication 972 and Schedule 8812 instructions
• IRS Publication 54, Tax Guide for U.S. Citizens and Resident Aliens Abroad (exclusion and the refundable credit)
• US Embassy London, Consular Report of Birth Abroad; SSA Federal Benefits Unit London
• GOV.UK, High Income Child Benefit Charge
• FinCEN, FBAR requirements for minors