Apply as soon as you know you’re eligible so you get all the money you’re entitled to.
You can claim tax credits at any time of year.
If you know your income will go down
Apply straight away if you know your income will drop to a level that means you’ll be eligible for tax credits.
For example, you could make a claim now if you found out your income is going to drop in 6 months’ time.
Usually, tax credits are backdated by up to one month from the start of your claim.