Self Assessment - Prepare your paperwork in advance

P60 Form (for employees) - this is your year end tax certificate of pay, showing the amount of PAYE and National Insurance Contributions deducted during the tax year. You can read more about the P60, P11D and other key HMRC forms in our handy guide here.

P11D - Employers must provide a P11D for all employees who have received taxable benefits of expenses during the previous tax year. A P11D should be completed for all employees earning over £8,500 per year (including Company Directors).

Bank Statements - these are essential not only to work out how much income you have received in the previous tax year, but also for details of any interest you're received from your bank. Typically, basic rate tax will already have been deducted before you receive the interest, so bear this is mind when entering your bank interest totals.

Self Employed Accounts - if you are a sole trader, you should have your accounts to hand.

Untaxed Income - you should obviously keep records of any untaxed income you have received - for example, work done outside your company structure, or if you make supplementary income on an "auction site".

Dividends - All dividends are taxed the same way, whether they're from your own limited company, a publicly traded company, or unit trust. When you receive dividends, you should also receive a "tax credit" voucher. When calculating your "dividend income", you should add together the amount of dividend received, plus the tax credit amount. You should read this detailed guide on dividend income, as it is a potentially confusing area.

Other Investment Income - this could be anything from share trading profits to income from letting out a property.