Which FICO score model does the mortgage lenders use?

Since most of the people have 3 FICO score, lenders consider the most adequate, concrete and usable FICO score instead of an inadequate abrupt one. If all the 3 FICO score are different from each other, then they use the middle score.
If two scores are same, then they consider that score.

The lenders also have their own preference about which credit score they'll check. For example, one lender can check score from Experian while others can check from ThansUnion.

As far as I know, mortgage lenders use various models of FICO score. Some lenders use the FICO classic 4 model at the time of giving home loans. Some even use the FICO 9.

These are the specific versions of the FICO formula that mortgage lenders use normally:

1. Equifax Beacon 5.0
2. Experian/Fair Isaac Risk Model v2
3. TransUnion FICO Risk Score 04

In some cases, if a person don't have a usable FICO score from any one of the three credit bureaus, the lender will consider the lower of the remaining two scores available. If any two scores aren't usable, then lenders will use the last one.