Tax Code change to 24LX until April 2024 from HICC?

Struggling with the calculation for a new tax code HMRC has given me, can someone kind help me understand please? I'm unclear if this is due to the income during 22-23 or 23-24. Current Tax Code: 943L Additions: 0 Deductions: - Underpayment from previous year: 337 - Child Benefit: 2800 - Total Deductions: 3137 Total tax free amount: 9433 New Tax Code: 24LX Additions: 0 Deductions: - Underpayment from previous year: 337 - Child Benefit: 5730 (1)* - Total Deductions: 6256 (2)* Total tax free amount: 247 2022-2023 net income (employee pensions already deducted) = 55395 No student loan repayments No private pensions No company benefits No maternity/paternity pay Finally, my 'projected' income is 57951 for 2023-2024 (I need to check if this is right but it seems in the ball park). Child Benefit total taken was £2400 roughly Referring to the references above. (1*) - what is this number? How is it calculated? Looking at the rules on paying back child benefits, I was paid £2400 in child benefit, and was £5395 over the 50k threshold for repayments, this number does not reflect either of these figures. Also I ticked the box to repay my tax over the 2024-2025 tax year, so why am I having to pay it now before April 2024? Based on a simple calculation I should repay ~£1300 of the £2400 borrowed (about 55% as I am 55% of the way into the 50-60k bracket for repayment). In the previous self assessment period (21-22) I elected to collect tax from my 22-23 tax code, (2*) I don't understand this number or how it is calculated

Hi

To give you a thorough explanation of you calculation and how your code has been subsequently adjusted, we will need to access and review your record.
Please contact us by webchat or post via Income Tax: general enquiries and we can confirm all adjustments made.

Thank you