High Income Child Benefit - tax repayment is higher than the actual benefit

I have completed a draft of my self-assessment and the figure for Tax repayable is higher than the actual benefit received. It's only £26 higher, but surely the tax should only be as much as the child benefit received? The auto calculation for child benefit was slightly off so I put in corrected figures (it balances out, just not over the actual tax year). The tax return is based on figures on the P60 and a very small amount of untaxed bank interest, so I don' think anything else could be affecting it. Any suggestions? Might it change when the tax return is submitted? Thanks.

Hi Liz,
The Higher Income Child Benefit Charge would be at most the full amount of Child Benefit received.
If there is a difference there would be something else that is causing this.
We would need to review your calculation for the difference.
If you file your Self Assessment and allow 3 working days to process to our systems and then contact HMRC to review.
Self Assessment: general enquiries
Thank you,