I kind of guessed that might be the case, so in this instance I have to just swallow loosing the personal allowance and hope for 2013/2014 the timing of payments of doesn't take me over this again?
In addition, is there anything I can do now that would allow me to reinstate the personal allowance, I pay into a private pension for example?
I'm afraid that you cannot backdate pension contributions. You can, however, use unused pension allowance for the three previous tax years in the current tax year. This might be useful if you are coming towards the end of the tax year and your earnings are over £100,000. You or your employer could make a one off contribution subject to the limit to reduce your "adjusted net earnings" which is the figure used for calculating eligibility for the personal allowance.You can read about pension contribution relief here and here and about adjusted net income here.
Thanks, good point about the current year.
As I'm filling in my online form I'm noticing a discrepancy between the tax I’ve paid on my P60 and what the online computation is working out I should have paid, a difference of 3k I appear to owe.
I presume this might be due to an in-correct tax code, though I don’t recall receiving a notice of a change for 2012/13, would my employer have received one if it changed automatically to adjust this if it needed doing?
What are the implications now if via PAYE, I’ve underpaid to the tune of 3k