If your tax payment due on 31 January is more than you expected there is still time to reduce the liability if you are prepared to take a risk. An HMRC tax planning opportunity is to invest in a company that qualifies under the Enterprise Investment Scheme (EIS) or under Seed EIS.
These investments enable you to deduct 30% or 50% respectively of the amount invested from your income tax bill. For example, £10,000 invested in a qualifying EIS company will enable you to deduct £3,000 from your tax bill.
Normally the shares need to be issued in the tax year in question, but it is also possible to invest in the following tax year and carry back the relief to the previous year.
You will need to get independent financial advice as these tend to be risky companies, particularly Seed EIS companies which are smaller start-up companies.