Most lenders add 3.5 times the main income and add one time the secondary income.

If you can't buy a property alone, this is certainly a very good choice.

If one of the party cannot pay the loan, the garantor is liable. It's essential to have an written agreement from a solicitor so that you and your partner be protected if one wants to leave or sale the property. And how much each party is contributing for the deposit and the mortgage repayments.

Example:

If you earn £30,000 a year, you can get a mortgage of £90,000 if you buy the property on your own or £150,000 if you buy it with someone else who has the same income.