There is no general age-based deadline for starting a PIP claim, but you should apply as soon as you think you may qualify because payment is not usually backdated indefinitely. Your claim normally starts when you contact the Department for Work and Pensions, and you will usually have one month to return the ‘How your disability affects you’ form by the deadline shown. Contact the DWP promptly if you need more time, as an extension may be possible depending on your circumstances. Check the latest guidance on GOV.UK, particularly if you live in Scotland where Adult Disability Payment has replaced new PIP claims.