Online filing deadline for submitting 2015/16 self assessment return if you require HMRC to collect any underpaid tax by making an adjustment to your 2017/18 tax code

This deadline is relevant for those individuals who complete a self assessment tax return online and who are employees. Where you have an underpayment you may request that HMRC collect any tax outstanding by making an adjustment to your tax code for the year 2017/18.