The deadline for submitting the 2012 Tax Return passed 31st January, with an instant £100 late submission penalty.
To avoid any further penalties, HMRC today warned people to file their Tax Return and pay any outstanding tax by May 1st, otherwise they will begin to charge a daily £10 penalty.
The penalty can be charged for a maximum of 90 days, so in addition to the £100 charge in January, the total penalties could accrue to £1,000 by August.
People should contact HMRC on 0845 900 0444 if they feel they have been sent a tax return but shouldn't be in Self Assessment as soon as possible, as surcharge penalties of at least £300 (or 5 percent of outstanding tax, whichever is higher) will start from August.