Penalties for non-compliance with corporation tax regulations can vary depending on the circumstances.
1 day late after deadline: £100
3 months late after deadline: Another £100
6 months late after deadline: Additional 10% tax geared penalty.  This is based on the unpaid tax at that date.
12 months late after deadline: Another 10% tax geared penalty of any unpaid tax.
If 3 returns are late in consecutive periods, the flat rate penalties increase from £100 to £500.