Self assessment payment on account due on 31 July 09 Jul 2024The second payment on account towards income tax self assessment liabilities and Class 4 national insurance contributions (NICs) for 2023/24 is due by 31 July 2024. The Institute of Chartered Accountants in England and Wales (ICAEW) is warning taxpayers to prepare for the 31 July 2024 payment deadline. Missing the deadline could prove to be expensive as HMRC's interest rate for late payments is currently 7.75%. Although the due date for paying ITSA and Class 4 NICs for 2023/24 is 31 January 2025, some taxpayers are required to make payments on account. The first payment was due on 31 January 2024 and the second is payable on or before 31 July 2024. The amounts are calculated according to the person's liabilities for 2022/23. Payments on account for 2023/24 are reduced where the person's liabilities for 2023/24 are less than that for 2022/23. The ICAEW stated: 'Care should be taken to ensure that it is appropriate to make a claim. HMRC may charge a penalty where a taxpayer fraudulently or negligently makes an incorrect statement in a claim to reduce a payment on account. The maximum penalty is the difference between the payment that should have been made and the amount that was paid.'