Can I trust tax credits calculation?

[Belindanomates]

I've read a lot about people getting tax credit overpayments and then having to pay them back. It seems to work ok when your income stays about the same but major changes can make it go wrong.

My situation:
2021-2022 tax year I was a student at the start of the year (eligible for CTC) and started working part way through the year making my annual income relatively low (eligible for CTC and WTC)

Recently looked at the future payments 2022-2023 and it is saying they will be paying me less WTC and more CTC, overall dropping total TC by about £50 a month. Will this be worked out based on 2021-2022's total income or my current employment's monthly income?

I have checked on entitledto and it seems broadly correct but I'm still concerned that I'll be overpaid. Also slightly complicated by the fact that I am on a 1 year contract at work so I'm not sure what will happen later in the year.

Have you checked to see if you'd be better off on UC. it's updated every month but tax credits are once a year.
That would stop the risk over overpayments due to increase/decrease in your income.

I've no idea why CTC would go up.
Tax credits are calculated over the year which is why it's important to update them with any changes to avoid overpayments.
I would also second looking at UC especially if you have rent to pay and do not have savings over 16k.

I wouldn't get any UC. I'm expecting this to be the last year I get tax credits at all as my income is pretty good, but it's worked out on last year's income or something?