You will not receive the £100 penalty as you have filed your tax return before the 31 January deadline, however the Collector will begin to charge interest on a daily basis starting from midnight on 1st February 2010 on the amount of tax unpaid. Interest is currently being charged at a rate of 3% on tax paid late.
You must also try to ensure that you pay the tax you owe by 28 February 2010, as any amounts relating to the 2008/09 tax liability that are still unpaid at this date will receive an initial 5% surcharge. There will then be a further 5% surcharge if any of the 2008/09 tax due remains outstanding after 31 July 2010.
Recently, the Chancellor announced an extension to the Business Payment Support Service for businesses affected by the current economic conditions. This service is designed for businesses who are worried about being able to meet tax, National Insurance or other liabilities owed to HMRC. You can get in touch with them to discuss payment options to help you deal with temporary cashflow difficulties on 0845 302 1435.