Newly self-employed need help!

PlutoinCapricorn

You mentioned random investigations: there is nothing that you can do to avoid these, as you say it is a good idea to be prepared just in case.

There are however "red flags" that would be likely to bring HMRC troops down on you. One is waiting until the last minute to file your return: this suggests that you are disorganised so it is worth seeing what records you keep. Another is not declaring bank interest: HMRC know who gets this, and if you don't declare it they may decide to see if they can find any other income that you are not declaring.
There are others but they are not relevant to you at the moment.

Horace

As you are very 'new' in the world of self employment, I would advise you to seek advice from Business Link or your local chamber of commerce as they will both offer free advice on setting up and running your business. You may also find it useful to go on some HMRC courses regarding self assessment how to complete tax returns and what you can and cannot claim for.

In short you need some proper business advice because at the moment you are in a vulnerable position because you are ignorant and I wonder if you have proper insurance too.

You need to keep proper books and note down your income and expenditure - business link/chamber of commerce can help you with these as their courses are very good and they will even help you do a business plan which is what you need.

PlutoinCapricorn

Bradc, I found this and think that it might be useful:

HMRC have launched a new teaching resource for secondary schools - Tax Matters.
The free, online interactive resource includes videos, quizzes and games, as well as key facts and figures, to help young people learn about tax and its role in society.
The new materials are primarily aimed at education professionals who teach Personal, Social, Health and Economic education (PSHE) and citizenship to pupils aged between 11 and 19. They are also designed to be used by charities and voluntary organisations that work with young adults not in employment, education or training.
The three Tax Matters modules - Income Tax, National Insurance, and Tax and Society - are available to download free
www.taxmatters.hmrc.gov.uk