Split Corporation tax amount for First Year Accounts

Need a bit of advice please, as never came across to this before. First year accounts, I know there are 2 tax returns to be prepared to cover the period from incorporation date until end of accounting year (let's assume 15/6/15-30/06/16) and you need to apportion the profit of £3000 and £600 tax, so:

period 15/06/15-15/06/16 Profit £5000, ctax £1000
period 16/06/16-15/07/16 Loss (£2000), ctax (£400)

What confuses me is:
-Is HMRC going to request payment of £1000 since this is what appear in the 1st tax return and are they going to carry forward the £400 instead into the following year?
-the full accounts prepared for Companies House shows the entire period and therefore £600 tax liability, so this shouldn't match HMRC?

Thanks in advance :-)