Do I need my partner's National Insurance number to claim Child Benefit?

What does GOV.UK say I need before I start?

The how to claim 'Before you start' list is short: the child's birth or adoption certificate if you have it, bank or building society details, your National Insurance number — if you have one, and your partner's National Insurance number (if you have a partner). HMRC's 18 May 2026 news page repeats 'National Insurance number for themselves and their partner, if they have one'. Which? (14 January 2024, and its April 2026 rates guide) lists the same four items.

The partner line is conditional: it applies if you have a partner. GOV.UK's High Income Child Benefit Charge page defines partner as someone you are not permanently separated from who you are married to, in a civil partnership with, or living with as if you were. The CH2 notes treat you as single for Child Benefit unless you live with a partner.

What if I cannot find my partner's National Insurance number?

Citizens Advice: if you do not have a National Insurance number, apply for one on GOV.UK. The apply page is for people who live in the UK, have the right to work, and are working, looking for work or have a job offer. GOV.UK says that application can take up to 4 weeks, and you can call the application helpline if it has been longer than that.

How do I unstick a claim when one NI number is missing?

1. 1
   Search the official lookup list first Payslip, P60, tax or benefits letters, HMRC app, personal tax account. Use Find your National Insurance number. Most 'we cannot find it' cases are a lost letter, not a missing number.
2. 2
   If they have never had a number, start that application on GOV.UK Citizens Advice points to Apply for a National Insurance number. GOV.UK: up to 4 weeks. That clock is for the NI number application, not a Child Benefit processing time.
3. 3
   Do not sit on the Child Benefit claim while you wait, if you can start it A separate GOV.UK line on the same apply page says you do not need a National Insurance number to start an application for benefits. If HMRC needs a number to pay the benefit, it contacts you. The how-to-claim list still asks for the numbers if you have them.
4. 4
   If you cannot use the online claim, use post or phone GOV.UK lists both. Citizens Advice: online or app claims can lead to a first payment in as little as 3 days; post can take around 3 months. Which? (April 2026) says a paper claim can take up to 16 weeks. Neither figure is a reason to invent a third processing time.
5. 5
   If you have no partner, do not invent a second number GOV.UK only asks for a partner's number if you have a partner. Living apart after a permanent separation is not the same as living together as a couple.

Why does HMRC ask for both numbers?

The claim needs to know who is in the household. Only one person can be awarded Child Benefit for a child. The High Income Child Benefit Charge looks at either person's adjusted net income. GOV.UK: if both of you are over the threshold, the person with the higher income is responsible for the charge. The partner's National Insurance number is how HMRC matches that person — it is not a second Child Benefit claim.

If one of you is not working, official notes still say that person should be the claimant. Their partner's number still goes on the form if they have a partner. Missing the partner field is not how you move the tax charge.

In shortGOV.UK asks for your number if you have one, and your partner's if you have a partner. Look it up on the official list before you delay. A missing number is not, on GOV.UK, a reason to skip Child Benefit until the baby is older.