Are you among the 700,000 taxpayers that missed the 31 January 2019 filing deadline for your 2017-18 self-assessment returns? If you missed the filing deadline then you will be charged a £100 fixed penalty if your return is up to 3 months late, regardless of whether you owed tax or not. If you do not file and pay before 1 May 2019 then you will face far greater penalties. A daily penalty of £10 per day, up to a maximum of £900 (90 days) will be charged from 1 May 2019. Further penalties then apply if your return is still outstanding for more than 6 months after the 31 January 2019 filing deadline. From 1 August 2019 you will be charged a penalty of the greater of £300 or 5% of the tax due. If your return still remains outstanding one year after the filing deadline, then further penalties will be charged from 1 February 2020.You can appeal against any penalties that have been issued and HMRC has said that they will treat those with genuine excuses leniently. However, you need to act fast and the excuse must be genuine and HMRC can of course ask for evidence to support any claim. An appeal must usually be made within 30 days of receipt of the penalty.