The key point with joint loans is that every party is equally and fully responsible for its repayment: even if only one of you defaults, you'll both still be entirely liable.
However, involving more than one person can make you eligible for a larger loan or better interest rates, and banks tend to be more willing to lend to two or more people together. Their risk is spread across two people's assets and potentially two incomes.
Why two incomes are better than one
Even for joint unsecured loans, two incomes make a default less likely so depending on your relationship and purposes for the loan, you're likely to have access to better rates than personal loans for individuals.
The relationship between borrowers is always taken into account on any joint loan application; some lenders only offer joint loans for married couples or blood relatives, while other providers set different criteria. Joint loans for couples are still available if you aren't legally registered as married, but be aware this can sometimes, although not often nowadays, narrow your options.
You'll also need to consider your combined circumstances and what it is you want to borrow towards. Even if you have two incomes, joint loans for bad credit may be harder to come by and it might be worth considering specialist poor credit history lenders. Similarly, with some lenders consolidation loans for couples may only be available as secured loans.
Find a suitable deal and compare
Use the above points to narrow your comparison down to find which lenders' deals are available to you as a joint application loan and prioritise the types of loan offered. Then, compare the features offered to find the best loan for your shared needs.
You should consider the amount you want to borrow, the loan term and the interest rates applied. Be aware that if your proposed loan doesn't fall within lenders' headline APR limits, you may be offered different rates. It's also quite likely that the rate applied to your loan will depend on the lender's view of your combined credit standing so if one or both of you have a tarnished history with credit you may find yourselves paying more.
Work out how much you'd repay overall and ensure that the monthly repayments are affordable to find the cheapest loans, and finally take into account their terms and conditions. Remember to factor in any early redemption charges if you think it's likely you'll want to clear the loan before the official end date.