It just impacts the rate they are willing to offer you until their individual cutoff that could range between 30-50% depending on your situation and the type of loan you're trying to get.

For example, to get an FHA loan with federal guidelines you have to have 31% or less DTI before the loan (front-end DTI) and 43% or less DTI after the loan (back-end DTI).

For most conventional loans the cutoff is between 45-50% depending on credit worthiness (you can go above this amount if you have really good credit, like near perfect).