Whether you're a company director or an LLP partner, you will need to gather a range of information before you or your agent completes your self assessment tax return. You will need details of all your taxable income, including details of your pension contributions; information about your income from letting property or land; your P60 or P45 from any employment you've had during the year; any capital gains or losses; details of your income from savings and investments within the UK; any life insurance gains or AVC refunds; and any donations to charity that are subject to Gift Aid. However, any cash, shares or funds that you hold within a tax-free ISA wrapper do not have to be declared.
If you're a company director, the company will normally have collected the tax due on your salary - along with any benefits in kind, such as a company car - via PAYE. However, your self assessment return may incur additional tax if any of your benefits were not taxed at source or, if you're a shareholder, you receive part of your pay in dividends and you're a higher rate taxpayer.
If you're an LLP member, you will be designated a share of the partnership's profit or losses in line with the partnership agreement, so you will have to wait for the partnership's tax return to be finalised before your own self assessment can be completed. You should declare only your share of the profits as part of your self assessment, and not the whole profits of the LLP.
If you're a new director or partner, you need to make sure that HMRC know that you're eligible to make a self assessment tax return. They should have written to you, but if you're in any doubt, you may need to contact HMRC directly. You will also need to know your ten-digit unique taxpayer reference (UTR).