Private pension contribution deduction reducing income to less than personal allowance

My personal pension contributions bring my net income down to less than the personal allowance, so I presumed I would not have to pay income tax. I have added my contributions to my tax return, but it does not appear to have reduced my taxable income. Am I doing something wrong or have I misunderstood?

Hi,

If you contact our Self Assessment team, we can review the calculation and an amendment can be done if necessary.

Self Assessment: general enquiries

Thank you.