Financial information in relation to your income needs to be included on a self-assessment tax return. Such information and where to find it includes the following-
Dividends received during the period – if you own your own limited company, or if you hold shares in other firms. Your accounts will provide this information for your own company, or you should have dividend vouchers with the relevant gross dividend information on for both your own company and dividends received from investments.
Salary – if you were employed either by your own limited company or by another employer during the period. This can be found on your P60 (received form your employer at the end of each tax year), or your P45 (received from your employer when you leave their employment).
Benefits in kind , received through your employment, such as healthcare or a mobile phone. This information can be found on your P11D form, again received from your employer once a year.
Self-employment income – if you were a sole-trader business. You will need your annual accounts to identify the profit figure required.
Rental property – if you have received income from renting out a property. You will need to declare the rental income, perhaps shown on statements received from your agent if you use one. You are also able to claim certain costs against this income when submitting the return, such as: mortgage interest paid (not the capital element of any repayment- subject to restriction), agent’s fees, insurance, any utilities paid by you as the landlord (not any paid by the tenants) and a 10% wear and tear allowance for furnished properties.
Interest – if you receive interest on savings (but not ISAs). You’ll need your bank or other investment statements for this.
Pension contributions – if you contributed into a personal (not occupational) pension, these contributions can offset some of your income and reduce your tax bill. You should have a statement from your pension provider, which show the amounts you have paid.
Gift aid donations – if you’ve made any charitable donations and claimed gift aid. Again, this will reduce your tax bill.
What if I can’t find the information
It is best to keep all the above records in one place during the year and get them together before you start completing your tax return.
However, life isn’t like that and if you can’t find the right document with the information on but you know you have received some income, it is better to make the best estimate you can and include this. There is space on the return for you to tell HMRC that you have an estimate and this will avoid the possible charging of penalties and interest on undeclared income, if it later comes to light that it should have been taxed.