THE NEW Year festivities are over and it is time to think about tax, with the January 31 deadline for file an online self-assessment return for the 2016/17 tax year fast approaching.

You probably do not need to worry about self-assessment if your only income is your wages, but about 747,000 Scots must complete a self-assessment form, including the self-employed and anyone with £2,500 or more of untaxed income, for example from a rental property.

A recent change lets some pensioners off the self-assessment hook. You usually have to complete a self-assessment tax return if the total amount of state pension exceeds the tax-free personal allowance of £11,000 for the 2016-17 tax year, even if it is your only source of income.

However, pensioners who first began to receive the state pension on or after April 6, 2016 - and have no other taxable income - no longer have to file a return. HMRC will instead send its own calculation of the tax owing for 2016/17. However, you should check the figures and pay any tax due by the end of the month.

Penalties for late filing can be harsh. There is an automatic £100 fine if you do not send the return by the end of January. If the return is still outstanding after three months, there is a daily penalty of £10 for up to 90 days. In other words, you could be hit with a £900 bill. Returns that are six months late attract a penalty of £300 or five per cent of the tax due, whichever is greater.

You cannot file a tax return unless you have a 10-digit unique taxpayer reference (UTR). The UTR was assigned when you registered for self-assessment and can be found on your documents from HMRC. If you cannot find a UTR, contact the self-assessment helpline (0300 200 3310). You must also enrol for the online service, but bear in mind that the process can take up to 10 days. If you are short of time, you can also log on with HMRC’s digital verification service, Gov.UK Verify.

The end of the month is also the deadline to pay the closing balance for any tax due for 2016/17. You might also have to pay the first payment on account for the tax year 2017/18, which is usually half the tax you owe from the previous year.

Again, there are penalties for late payment of tax. Any tax not paid after 30 days incurs a penalty of five per cent of the unpaid tax. There is an additional five per cent penalty if the tax is still outstanding after six months and a further five per cent if it is 12 months late.

It is therefore important to get on top of the paperwork and to meet the deadlines for both filing the return and any payment of tax.

Dawn Register, a tax partner at accountancy firm BDO, said: “If you miss the deadline, you will start to incur penalties. HMRC will also estimate your tax bill and could take action to recover any debt. If you can’t afford to pay the tax owing, you should still file the return and then contact HMRC as soon as possible – preferably before the deadline. If you can prove genuine hardship, you can often come to a ‘time to pay’ arrangement with HMRC.”

There are a few simple steps to follow to make sure you can file your return correctly and on time.

First, only fill in the relevant sections of the form and remember that ISAs, premium bonds, lottery wins, gambling winnings and the occasional eBay sale do not need to be included.

Tick the box if you are a Scottish taxpayer. You qualify as a Scottish taxpayer if you live primarily in Scotland.

Remember to send the form even if you do not owe any tax, otherwise you will incur penalties and always check whether HMRC wants gross figures – which include tax - or net figures – which exclude tax.

Claim any tax relief on charitable donations and personal pension contributions. Stephen Sutherland of accountancy firm John M Taylor & Co, said: “Many people don’t appreciate that reporting these amounts can reduce your tax bill if you are a higher-rate taxpayer.”

Finally, check all your numbers thoroughly before pressing submit. As Ms Register said: “The onus is on the individual to fill in the form correctly. HMRC also penalises people who make mistakes.”