Thanks for your question
Whilst it seems you are paying more tax, the change to the tax code allows the state pension to be paid tax free (in essence) as whilst state pension (as well as your Civil Service pension) are taxable incomes, tax cannot be directly deducted from the state pension, so its covered fully by your entitlement to tax free allowances, first, then leaving the balance of unused allowances to be used against your Civil Service pension.
SO if you compare the tax you pay at this time each month x 12 and then compare it with your last P60 from the Civil Service, you will find the tax you pay is less per month/ year, as the income you receive is less per year.
HOWEVER as you have turned 65 your tax free allowances should not be £9440 but increased to £10,500 so this does need to be rectified by HMRC so ring them and ask them to review your tax free allowances, and increase them accordingly.
(Please note that age related allowances are being phased out, but will remain at £10,500 until the personal allowances - which are currently at £9440 are in line with this amount, then there will be just one amount of personal allowances awarded for all)
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