What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

The thing with Jumbo products is that each lender can make up their own rules - which result in a variety of qualifications that vary from lender to lender.For your specific example under today's conditions (8/8/2022), a $3M Purchase Price at 20% down will get you the following: - With a 740 Credit Score: 6% interest with about $200 of lender credit ($6000 in lender credit if you have an 800)- You will need 18 months of reserves (PITIA of the new property x 18)- Likely 6 months of reserves for the departing residenceLike others have mentioned, you should shop around for Jumbo products since some lenders have opportunistic terms that are dependent upon their investors at the time.

.- Credit - This is your credit history and represented through a score.

Currently only have 12k in savings...but I do have a credit score of 744.

@Carlos Martinez- 1) if you have  no property yet and  are trying to get pre approved - and  trying to decide on a lender to use for this - you DO NOT  need to have the  credit pulled  yet  2) contact whatever lenders  you want on the same day and  provide the same  criteria  ( price / loan amt / credit score/ loan program ) and  ask  for   quotes  from them   and  any other  questions you have  3)   if any are not willing or able to  provide quotes - take them off your list  4) make a  decsion on one lender from the feedback  received and proceed with the one  lender for the  formal  pre approval and  have them pull the  formal  tro merge  credit report  and provide them with all your data ( paystubs / bank statements  / w2s  etc ....)   5) once pre approved -  begin to aggresively  house  hunt  6) when a  property is  found and you get into contract - you can  cost compare the lender  you are  pre approved with  with any  other lender and make final decision to proceed with rate lock with the lender you choose 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Get a FREE EIN and get tradelines and move all credit to business credit cards/lines/loans that DO NOT report to personal credit to boost your scores! 

Another vote for rent. 2 more reasons. 1) They decide they don’t want internet, get it free from work, see it advertised everywhere for $50, or your version isn’t fast enough, so no longer pay for it. 2) you suddenly become subject to rent increase caps and you’ve set the rent below market forever. 

You could look into pursuing a dscr loan - this type of loan is perfect for a rental property as it uses rental revenue along with your credit score to qualify.

For a 1.2MM Primary you should only need 5-10% down based on credit scores.