How joint qualification works
Lenders add both gross incomes and apply a maximum DTI. Your combined income × the DTI limit, minus your current monthly debt payments, is the most a new payment can be. The calculator then works out the loan that payment repays at the note rate ÷ 12.
Worked example
You earn $5,000 a month and your co-borrower $4,000. With $1,500 of debt payments and a 36% limit, you could pay up to $1,740 a month. At 11% over 5 years that repays $80,027.88, with $24,372.12 of interest. Your DTI now is 16.67%.
Co-borrower or co-signer?
A co-borrower shares the loan and usually its proceeds. A co-signer guarantees it without owning what it buys. Either way, both are fully liable, and the loan shows on both credit reports.
What this calculator assumes
A fixed note rate, equal monthly payments and one DTI limit. Lenders also look at credit scores, which may lower what they offer.
Borrowing in the UK?
The country choices above the inputs open separate local pages. UK lenders check joint affordability from take-home pay and spending rather than a DTI ratio. Choosing United Kingdom opens that page and resets the inputs; amounts are not converted.
For a UK joint loan, use the UK joint loan eligibility calculator in pounds.
Inputs for the US joint loan qualification calculator
Your gross monthly income
Your monthly income before tax and other deductions.
Co-borrower's gross monthly income
The same for the other applicant.
Monthly debt payments
Both your rent or mortgage, car, student loan and minimum card payments.
Maximum debt-to-income ratio
The limit lenders use. 36% is a common guide.
Interest rate
The yearly note rate you expect.
Term
How long you'd take to repay, in years.
CALCULATOR QUESTIONS
US joint loan qualification calculator questions
Does adding a co-borrower increase how much I can borrow?
Usually, because the lender counts both incomes. Their debts count too, and both credit histories are checked.
How is DTI calculated for a joint loan?
Add both applicants' monthly debt payments and divide by both gross monthly incomes.
Who has to repay a joint loan?
Both borrowers, for the full amount.
Can a co-borrower with bad credit hurt the application?
Yes. Lenders may price or decline the loan based on the weaker credit history.