To claim DLA for a child you need to be their parent or look after them as if you’re their parent.
For more details, visit the gov.uk DLA for children overview or read the DLA for children easy-read guide
To apply, visit Gov.uk to download a claim form and notes on how to complete it (you'll need to print the form, complete it and send it back).
If you can't print the form yourself, you can phone the Disability Living Allowance helpline (Monday to Friday, 9am to 5pm) and ask for a printed form:
Telephone: 0800 121 4600
Text phone: 0800 121 4523
Relay UK (if you cannot hear or speak on the phone): 18001 then 0800 121 4600
Video relay service for British Sign Language (BSL) users