You need to renew if you have been sent an Annual Declaration form with an Annual Review notice. You do not need to renew if you have only been sent an Annual Review notice as your claim will be automatically renewed.
You must also inform HMRC promptly of changes to your circumstances which affect the amount of tax credit claimed e.g. marriage, reduced hours of work etc.
If you need to renew but have not done so, please contact us for advice.