in order to compare records in Quick Base, you will need to change the Key field of your data form the default [Record ID#] field to to be something which is also Unique, but which will let you make a relationship so that the relationship knows which other record you want to compare to.
If the data is being imported by Excel where you can create a formula text field, then my suggestion is to create a new field in the format Acct#-YYYY-MM.
You can either re-import your current data or make a formula field in Quick Base to have that format and then change the formula field to a text field and the data for the Key field will be populated. Then change the Key field to that concatenated field.
Then you will be able to build a formula to be the Last year Key field and make a relationship with the last year records to bring in the data.
Post back if you want to go ahead and do that, but get stuck along the way.