The amount that can be offered, and how it is calculated, is dependent upon the lender themselves. This is why we encourage looking around different lenders to find the best deal.
For a sole trader, the net profits of your business prove your earnings as these belong to you. Ultimately, you will need to show lenders your income for the past two to three years to calculate your average income.
Similarly, if you are a contractor where money is taken from your payslips for tax and national insurance, lenders will analyse your application through the same process as sole traders. With this in mind, you will need payslips for the previous six months.
If you own a limited company, lenders will look at your salary and dividend payments for the past two to three years. Alternatively, if you are part of a business partnership, lenders will only need evidence of your share of profits.