Because a mortgage is a loan, so they review your income/finances and if they feel it's a risk due to those reasons, they won't offer. Good landlords should also turn you away if you're monthly income will barely cover the rent, because that too is a risk. Most landlords will accept because ultimately, a person will scrounge what they have to keep a roof over their head. If $2400 is half of your monthly income, you need to find somewhere else to rent or a house that's more affordable. When I bought my house 10 years ago, I was approved up to $180k, but I opted for a $75k home and dumped $40k in to a complete remodel. My house us now valued at $220k and I owe less than $60k on it. A home can be an appreciating asset and is a good investment but you have to be smart with your money!