ADVICE ON RECORD KEEPING FOR TAX PURPOSES
If you're a UK taxpayer you should keep a record of the tax you pay each year and certain other records relating to your income. You'll need these if HM Revenue & Customs (HMRC) asks you to complete a tax return, or to back up one you've already completed.

Income from employment:
These are the documents containing details about your pay and tax that your employer must provide you with and that you should keep:

• P45 (if you leave your job during the tax year, your employer will give you form P45 and you
  should keep part 1A of this form) 
•  P60 (your employer should give you this by 31 May after the end of the tax year)
• details of your taxable expenses and 'benefits in kind' (non-cash benefits), such as a company car or health insurance (your employer should give you these by 6 July after the end of the tax year)
• your payslips or pay statements
• certificates for any 'Taxed Award Schemes'
• information about any redundancy or termination payment (if relevant)

Benefits Information You should also keep:

• a note of the amount of any tips or gratuities and details of any other taxable receipts or benefits not included in any other documents.
• information about benefits in kind (for example meal vouchers) received from any person or
  company, other than your employer, in connection with your employment.

Benefits records:

• You should keep any documents relating to: social security benefits, Statutory Sick Pay, Statutory Maternity Pay and Jobseeker's Allowance.

Pensions Information You should keep:

• P160 (part 1A), which you may have been given when you retired and started receiving a pension paid by your former employer
• P60 - a certificate which the payer of your company pension may give you, showing the
  amount of your pension and tax deducted
• any other certificate of a pension you received and the tax deducted from it
• interest, dividends or other income from UK savings, investments or trusts

Banking Information You should keep:

• bank and building society statements or passbooks
• statements of interest and any other income received from your savings and investments, for
  example, an annuity
• any tax deduction certificates supplied by your bank
• dividend vouchers received from UK companies
• other vouchers such as scrip dividend vouchers
• unit trust tax vouchers
• life insurance chargeable event certificates
• details of any income you receive from a trust

Investment Information You should also keep:

• details of exceptional amounts you used to fund your investments, for example, a sum you inherited or any other windfall
• copies of correspondence and other documentation relating to your savings and investments

Record keeping for landlords:-
Income from property. If you get income from letting out a property, you'll need to keep a note of details such as all rents received and expenses paid.

Foreign income or gains:-
Depending on the types of foreign income or gains you have, the records you need to keep will include dividend vouchers, tax certificates and personal financial records.

Income from employee share schemes or share-related benefits:-
You should keep information on any share options awarded or any share participation arrangements.

Capital gains or capital losses:-
The records you'll need to keep will depend on your circumstances, but in general should include contracts and other documentation relating to assets you have bought, sold, exchanged, given away or acquired.
You should also keep any bills, invoices or other evidence of payment records such as bank statements and cheque stubs for the costs of purchase, improvement or sale of assets and copies of any valuations used in your calculations.

Business income or income from self:-employment
If you're self-employed or in business, there are certain records you legally have to keep. There are also many good business reasons for keeping good records.

HOW LONG MUST YOU KEEP YOUR RECORDS?
If you're asked to complete a tax return, and are not running a business, you will normally have to keep your records for at least 22 months from the end of the tax year to which they relate.

In some instances, for example documents relating to the purchase or improvement of assets, it's advisable to keep them until at least 22 months after the end of the tax year in which you dispose of the asset. They will help you calculate any capital gain or loss and respond to any enquiries by HMRC.

The Business Link website publishes guidance for self-employed people and small businesses on how to set up a basic record keeping system.
More on record keeping for businesses