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Can a Co-Signer Help You Qualify for a Mortgage?

Can a co-signer help you qualify for a mortgage?

Michael Jensen, Mortgage and Finance Guru
, Mortgage and Finance Guru

First, it is important to define what a co-signer for a mortgage is. A co-signer is someone who is listed on the mortgage note but does not hold an ownership interest in the property. In short, the co-signer is responsible for the mortgage, along with the borrower,  but does not own the home. A mortgage co-signer typically does not live in the property you are getting the mortgage on. For example, if you ask a friend or relative to help you qualify for a mortgage and they are willing to be on the mortgage but not own a stake in the property, you are asking her or him to be a co-signer.

A co-signer is different than a co-borrower, who is listed on the mortgage note but also holds an ownership interest in the home. The most common example of co-borrowers in when spouses apply for a mortgage on a home they intend to own and live in together. In the cases when co-borrowers do not live in the property, they are called non-occupant co-borrowers.

A co-signer can help you qualify for a mortgage but there are several important points to keep in mind. First, when two people apply for a mortgage -- be it a borrower plus a co-signer or as co-borrowers -- the lender uses the lower credit score between the two applicants to determine your mortgage eligibility and loan terms. The lower your credit score, the higher the mortgage rate you pay. If your credit score is too low, you may not be eligible for certain loan programs.

So even though your co-signer’s credit score is high, it may not matter if your credit score is low. The example below demonstrates what credit score lenders use when you apply for a mortgage with a co-signer. Please note that if an individual has two credit scores, the lender uses the lower score and if an individual has three credit scores, the lender uses the middle score.


Credit Bureau A: 630

Credit Bureau B: 640

Credit Bureau C: 660


Credit Bureau A: 740

Credit Bureau B: 760

Credit Bureau C: 800

In the scenario above, the lender uses the 640 credit score -- the lowest of the applicants’ middle scores -- to determine the borrower and the co-signer's ability to qualify for the loan and to set their mortgage terms. This example demonstrates how having a co-signer with a higher credit score may not help you if your credit score is too low.

Where a co-signer can be more helpful is if she or he earns a significant monthly income and have relatively low debt expense. With standard mortgage underwriting, when you apply for a mortgage with a co-signer, her or his monthly gross income is added to your monthly gross income to determine the mortgage you can afford. On the other hand, her or his monthly debt expense is added to your debt figure.

The higher your combined monthly gross income relative to your combined monthly debt payments, the higher the mortgage amount you qualify for. The example below demonstrates the benefits of applying for a mortgage with a co-signer. This example assumes a 30 year fixed rate mortgage with a 4.000% mortgage rate.


Monthly Gross Income: $2,500

Monthly Debt Payments: $500

Mortgage Borrower Can Afford on Own: $125,000


Monthly Gross Income: $3,500

Monthly Debt Payments: $300

Applicant + Co-Signer

Combined Monthly Gross Income: $6,000

Combined Monthly Debt Payments: $800

Mortgage Applicant Can Afford with Co-Signer: $366,000

This example demonstrates how a co-signer can potentially enable you to qualify for a higher mortgage amount but also highlights the importance of the co-signer’s financial profile. All of the co-signer’s monthly debt payments are added to your debt payments to determine the loan you can afford. If your co-signer has too much debt relative to his or her income -- such as a high mortgage or monthly rent payment -- she or he may actually reduce the mortgage you qualify for.

Use our TWO PERSON MORTGAGE QUALIFICATION CALCULATOR to determine the mortgage amount two people can afford

It is important to highlight that if you apply for a mortgage with a co-signer and the lender uses manual underwriting -- which is required if you are requesting an exception to a guideline or if your application involves special circumstances -- the lenders applies a 43% debt-to-income ratio to the borrower's income alone to determine what size mortgage you qualify for.

In short, a debt-to-income ratio determines how much of your monthly gross income you can spend on monthly debt expenses including your mortgage payment, property tax, homeowners insurance as well as other debts such as credit cards and car, personal and student loans.  The lower the debt-to-income ratio used by the lender, the smaller the mortgage you qualify for.  This guidelines applies to manually underwritten loan applications even if the combined income and debt expense for you and the co-signer would enable you to qualify for a higher mortgage amount. 

We should also emphasize that if you are a co-signer on a mortgage you are required to provide the same information and documentation as the borrower. This means the lender pulls the co-signer’s credit report and the co-signer is required to submit a loan application with detailed personal and financial information.  Plus, the co-signer is required provide documents including tax returns and bank statements. In short, the co-signer must be comfortable undergoing the same scrutiny and diligence that is applied to the borrower.

The mortgage also appears on the credit report for both the borrower and the co-signer.  So if the borrower has a late payment or other issues with  the mortgage, it may impact the co-signer's credit score as well.  Additionally, if you are a co-signer the monthly mortgage payment is included in your debt-to-income ratio when you apply for a mortgage or other type of loan in the future, which can make it more challenging to qualify or reduce the loan amount you can afford. 

The final point to highlight about applying for a mortgage with a co-signer is that the qualification guidelines may be different. You may be required to make a higher down payment or the lender may apply a lower debt-to-income ratio, which reduces the mortgage you qualify for.

Mortgage underwriting and qualification requirements vary by lender and loan program. It is important to understand the guidelines that apply to your situation and how the loan amount you qualify for and your required down payment change if you apply for the mortgage as a sole borrower as compared to applying with a co-signer.

In closing, applying for a mortgage with a co-signer offers benefits but there are several possible disadvantages as well. The table below shows mortgage terms for leading lenders in your area. We always recommend that you contact multiple lenders to understand your financing options and how a co-signer could potentially help you qualify for a mortgage.

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"B2-2-04, Guarantors, Co-Signers, or Non-Occupant Borrowers on the Subject Transaction."  Selling Guide: Fannie Mae Single Family.  Fannie Mae, June 5 2018.  Web.

"Non-Occupant Borrower Fact Sheet."  Originating & Underwriting.  Fannie Mae, July 2019.  Web.

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About the author

Michael Jensen, Mortgage and Finance Guru

Michael is the co-founder of FREEandCLEAR. Michael possesses extensive knowledge about mortgages and finance and has been writing about mortgages for nearly a decade. His work has been featured in leading national and industry publications. More about Michael

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