Taking deductions made via tax code in current self assessment

Hi I currently have a K622 tax code, which I setup on the phone at the start of this financial year. This is because I knew the 23/24 tax year I had underpaid and so this tax code was put in place so I be clear of paying a self assessment bill ahead of time. However I can't seem to find where I can this into the self assessment forms? At the moment it shows I owe £2400 which isn't the actual case since I've had this taken from my tax code over the course of this year. Thanks

Hi
It depends on the breakdown of the code as to how you would declare the details. If you contact HMRC we can access the record to advise you Self Assessment: general enquiries