Taxpayers face Hallowe'en tax horror Around 10.6m taxpayers have been told this year that they are required to complete a self-assessment tax return. This will include many higher-rate taxpayers, the self-employed and those who have a second income, be it from a buy-to-let property or additional freelance earnings, for example. A spokesman for HMRC said online forms would also be processed more quickly, so those who have overpaid their tax should get a rebate quicker. Because of the instant penalties for late forms, those who are concerned about missing the October 31 deadline should register online instead. This can be done at hmrc.gov.uk/online. HMRC advised all those sending a paper tax return to obtain proof of posting, as this provides evidence of the date of dispatch in the event of an appeal against a late-filing penalty. Taxpayers should be aware that the £100 fine can easily escalate. If a return is still outstanding three months later there can be additional penalties of up to £10 per day, up to a maximum of £900. After six months a further penalty of 5pc is added, or £300, whichever is greater. After a year taxpayers can face a further 5pc surcharges. Taxpayers will also face interest charges, plus further penalties on outstanding tax bills.