If your personal tax affairs are something of a Frankenstein’s Monster, tax body ICAEW has today warned those still filing paper Self Assessment tax returns to beware the October 31st deadline – now just ten days away. Around 11 million individuals must file a Self Assessment this year, and around 17.5% still file on paper. While the deadline for online filing (as well as payment of any owed tax) is January 31st, the 1-in-6 people still filing using a paper form must submit their return by the end of October.

Failure to meet either deadline or pay owed tax on time will result in an instant £100 fine from HMRC – a penalty which hit some 700,000 taxpayers last time around. There are further penalties at 3, 6 and twelve months. Anita Monteith, ICAEW Tax Faculty manager, points out that those who miss the paper filing deadline this year could use it as an opportunity to move their personal tax online and avoid fines:

“If the thought of filing your tax return before the end of the month gives you the creeps, you can always register for online filing at www.hmrc.gov.uk, which will give you until 31 January 2015. But don’t let your tax return become a skeleton in the closet that comes back to haunt you – plan ahead and leave yourself plenty of time to get the job done.

“Remember, if you have been sent a return or a notice to file one, you’ll need to fill it in even if there’s no tax to be paid or you’ll face a penalty.”

Those wanting to use online filing for the first time must leave a few weeks in order to complete the registration process, in order to receive their Unique Taxpayer Reference number (if they don’t already have one) and their HMRC Online Services login details. You can read more details on filing a Self Assessment online here.

HMRC issued its own warning last week, echoing ICAEW’s advice and directing unsure filers towards official advice on the GOV.UK website or the Self Assessment helpline on 0300 200 3310, available 8am-8pm, Monday to Friday, and 8am-4pm on Saturday.