Makes it hard to make the numbers work, especially once you account for the potential tax increase from the new assessed value if you are buying it much higher than what it's currently assessed at.

Cap rate underwriting is an incomplete approach on assessing deals.

In a lot of areas there are tax trade-offs (TX has no capital gains but has higher property taxes in many cities), (in my PA market the capital gains are low but the property taxes are high VS assessed value), (in MO where I invest the capital gains rate is alright as is the property taxes though there's a growing, solid economy here). 

Also keep in mind, with condos, you have growing annual maintenance fees and potential special assessments.

They are in the business of lending, but they also have to assess RISK and an inexperienced rehabber, buyer, etc. is a huge risk for their investors. 

You can use the county assessed value x the county common level ratio or an appraisal. 

You'll want to assess the big ticket items for age and condition.

The rate reduction was only going to be ~$140/$100k assessed, so shouldn't be a deal breaker in evaluating properties.

If there are structural repairs needed on your home, then are they needed on multiple homes, and does this mean you may see a $20k assessment surprise in the next year or two?

There is usually a 1-page form that you have to complete and then attach details of the comps and/or reasoning why they should adjust their assessment.