Worried about getting a fine from tax credits

[StrawberryInSpace]

Just had renewal form through, the amount that's down on the form as what I pay in childcare fees is £99 per wk but after lengthy calculations I worked out my average weekly payout for childcare is £69... Genuinely thought I had given them a correct up to date figure but I must not have done. It must be that I didn't think to tell them when my ds started getting 15 hrs free.
Now I'm worried that once I tell them I might be fined for not letting them know about a change as its been so long. Has this kind of thing happened to anyone else? Have you ever been fined by them? Or will it just be repaying what I shouldn't have received? I think it will be a v large overpayment
I'm so annoyed with myself for not keeping on top of it.

How could 15 free hours only be worth thirty quid?

If you fess up you should be fine. They will recover it and it might be by reducing further awards but whatever you do make sure its YOU that tells them

Yeah this happened to me too! I just explained i'd made a mistake and was really sorry. They were absolutely fine, I had quite a large overpayment as I'd stuck my head the sand for so long (totally regret that).. It was about £800 and I just repaid it from my next years award. They said they could have lowered it so it was more manageable but I just wanted it out of the way. Just explain, they will be fine! And easier to deal with HMRC than bloody concentrix

They don't fine you but you will have to pay back any overpayment. It is usually paid back ( up to a certain %) from your current payments.

Penguin- Maybe it is because the 15 free hours is term time only, and op may be calculating costs over a year accounting for a lower figure.