When there are two consecutive late filings of corporation tax returns, the third late filing of a return will generate a £500 late filing penalty and not the "standard" £100 late filing penalty.
These penalties can get even greater should the two consecutive late filings be more than 3 months after the due date. In this case, the £200 late filing penalty increases to a massive £1,000 penalty.
An important time to ensure that these type of penalties don't creep up on you, is when your company starts out. Often your first financial year-end is longer than 12 months, so there are automatically two tax returns required for the first financial year-end. If both of these returns are late, you could potentially be looking at the £500 penalty for your next financial year!