Under certain circumstances it is possible to arrange the collection of unpaid tax through your PAYE coding rather than making a balancing payment on 31 January 2019.  This  will depend upon the amount outstanding and the amount of income taxable under PAYE. There is a further condition that the return is submitted to HMRC online before 30 December 2018 in order that the 2017/18 tax be collected by amending the 2019/20 PAYE coding.