It depends on several factors.
Where did you get your score of 620? Is that your mid score?
How are you paid? Are you hourly or salary? Is any part of your 100K income from overtime, commission or bonuses & if so, do you have a 2 year history of receiving it? Are you self employed? Do you take just the standard deductions on your tax returns or do you itemize your deductions?
How did you calculate your debt to income of 10%? Is this just your current monthly debts or did you add an estimated housing payment?
How much money do you have for your down payment? FHA requires a down payment of 3.5% while a conventional loan will require 3 to 5% down.
If your mid score is 620 as pulled by a lender and your DTI is really 10% based on how a lender will calculate your income and you have enough money for a down payment, then YES you could qualify for a 300K mortgage in Phoenix.
Take a look at the recommendations from some of my past clients on my Trulia profile by clicking the link below my phone number.
Please feel free to contact me for more information or help.
Senior Mortgage Banker
Lending in ALL 50 states
Great Plains National Bank
Apply Online: https://secure.smartapp1003.com/102471/?loanofficerid=106115