Thank you for reply,
The £1000 pension began 2008/9 and was not added to tax calculation until 2011/2012 and again in 2012/2013.
It is a P800 caculation for these years and my code has changed to repay tax owed. which is not so if this taxed at source pension was not used in the tax calculation.
Thank you again
I have not been able to convince the tax lady that this £1,000 pension is wrong to use in my tax to pay calculation I just get 'it is sorted out in the codes'
This £1,000 is the cause of the underpaid tax issue having been used my calculation.
My total pension add up to £18,000 total gross