I have a hefty tax bill to pay for 2011/2012 tax year due to a taxable event gain. However if I pay a one off payment into my pension will I be able to use that to reduce my last year's tax bill? In other words can I include a one off payment made this year in my last year's tax return?
Unfortunately no. The tax relief applicable to a pension payment can only be claimed for the tax year in which the pension contribution is made. However, given the size of your tax bill and its complexity I suggest that you employ the services of a tax accountant to help minimise it. If you don't already have one then you can locate an accountant via the ICAEW directory of chartered accountants.
Money to the Masses