Unfortunately this is happening to a lot of people at the moment and there has been a rush on Universal Credit claims, but unless your job has ended you are able to stay on Tax Credits if you're already getting them.
If you get Child Tax Credit this won’t stop anyway whether your hours reduce or your job ends - it’s based on you having responsibility for a child and not on the fact that you work.
Normally getting Working Tax Credit depends on the number of hours you normally work - this could be 16, 24 or 30 hours a week - it depends on your circumstances....BUT...
HMRC announced, on 4th May, that people temporarily working reduced (or no) hours due to coronavirus, or who are being furloughed, will not see a change in their Tax Credit payments - so long as they are still employed or self-employed - as they will be treated as working their normal hours until the Job Retention Scheme and Self-Employment Income Support Scheme close, even if they are not using either scheme.
So you do not need to contact HMRC about your change in hours and can stay on your Tax Credits.
Trouble is that even though your wages have dropped you may not see any increase in your Tax Credit award - this is because the way Tax Credits work is that WTC can only be increased due to a drop in your income if your income goes down by £2,500 or more over the current tax year. And we’ve just started a new tax year on 6th April 2020.
But if your wages continue to be lower after the Job Retention Scheme and SEISS scheme end (probably early July) then if you think over the year they will drop by more than £2,500 you can phone the Tax Credit helpline 0345 300 3900 or write to the Tax Credit office on any letters they’ve sent you, or online using the Government gateway and they may take this drop into account.
Are you getting Housing Benefit for help paying your rent?
You should let the HB Office know about the drop in wages, so that your HB is increased.
If you're not already on Housing Benefit you will not be able to make a new claim for HB. Instead, you might want to think about Universal Credit. And even if you’d be better off for a while, that might not be the case when you get your hours back - but you’d then be stuck on UC. There’s lots to think about with Universal Credit – and you might prefer to stay on Tax Credits while you can- it’s best to speak to a Benefit Adviser to check what’s best for you.