Couple of questions about child tax credit

[Linnet]

At the moment we claim ctc as a couple, between us we work over 30hours, split 20/22 so total 42 hours between us. I have the option of increasing my hours to 25 hrs a week.

According to the renewal form notes it says to inform them if your hours drop below 30hours if you claim as a couple.

On our renewal letter it says that they assume for 2018/2019 claim we will earn between £10,000 and £15,000 for the year(not actual figures given) and our earnings will still be within this bracket.

So do I need to tell them about my change in hours seeing as we are still working more than 30 hours between us? And would this mean that we have to move onto UC, is it classed as a change in circumstances?

Bump

No a change in work hours would not mean switching to UC unless your hours dropped significantly and you were getting working tax credits and no longer qualified for those. Even then you wouldn't be forced to switch but might be better off on UC. It is best to let tax credits know if your hours are increasing though as your wages will be slightly higher. Unless your earnings are going to be increasing by more than 2.5k over the year it wont make a difference to your payments but I think it's always best to let them know.