1 December 2017 – Due date for corporation tax due for the year ended 28 February 2017.19 December 2017 – PAYE and NIC deductions due for month ended 5 December 2017. (If you pay your tax electronically the due date is 22 December 2017)19 December 2017 – Filing deadline for the CIS300 monthly return for the month ended 5 December 2017.19 December 2017 – CIS tax deducted for the month ended 5 December 2017 is payable by today.30 December 2017 – Deadline for filing 2016-17 self-assessment tax returns online to include a claim for under payments to be collected via tax code in 2018-19.1 January 2018 – Due date for corporation tax due for the year ended 31 March 2017.19 January 2018 – PAYE and NIC deductions due for month ended 5 January 2018. (If you pay your tax electronically the due date is 22 January 2018)19 January 2018 – Filing deadline for the CIS300 monthly return for the month ended 5 January 2018.19 January 2018 – CIS tax deducted for the month ended 5 January 2018 is payable by today.31 January 2018 – Last day to file 2016-17 self-assessment tax returns online.31 January 2018 – Balance of self-assessment tax owing for 2016-17 due to be settled on or before today. Also due is any first payment on account for 2017-18.