High Income Child Benefit Tax Charge - overpayment calculator error?

When I calculate how much I need to repay why would the figure in the Self Assessment online be roughly 3 times higher than what I should be repaying? My net adjusted salary is entered correctly as is the tax I paid so the figures I have entered are correct but the repayment of Child Benefit is not being calculated correctly, what do I do?

Hi
If you submit the tax return, and contact Self Assessment after 72 hours we can view the calculation and advise accordingly.
You should also check your tax code to ensure any allowances outside the Personal Allowance have been included on your return.
Self Assessment: general enquiries
Thankyou.