Tennessee assessors don't physically inspect every property to determine its value. Instead, they use mass appraisal—statistical models that estimate property values across entire neighborhoods based on sales data, property characteristics, and market trends.
This system is efficient and generally accurate for neighborhoods as a whole, but it can miss important details about individual properties. Understanding how mass appraisal works helps you identify when your property might be over-assessed and why you have grounds for an appeal.
How Mass Appraisal Works
Assessors use computer models to analyze thousands of property sales and characteristics, creating statistical formulas that estimate values. They don't visit your home unless there's a specific reason.
In This Guide
Mass Appraisal vs. Individual Appraisals
There's a crucial difference between how assessors value properties and how a real estate appraiser values a single property:
Mass Appraisal (Assessors)
- Values thousands of properties at once
- Uses statistical models and formulas
- Based on property records, not physical inspection
- Looks at neighborhood trends, not individual details
- Efficient but can miss property-specific issues
- Updated every 4-6 years (reappraisal)
Individual Appraisal (Real Estate)
- Values one property at a time
- Physically inspects the property
- Considers all condition issues and features
- Uses recent comparable sales for that specific property
- More accurate for individual properties
- Done when property is sold or refinanced
Why This Matters
Mass appraisal is designed to be accurate for neighborhoods overall, but individual properties can still be over-assessed. Your home might have condition issues, errors in the property record, or negative factors that the statistical model didn't account for. That's why appeals exist—to correct these individual inaccuracies.
How Assessors Determine Values
Tennessee assessors use several data sources and methods to estimate property values:
1. Recent Sales Data
Assessors analyze recent property sales in your area to understand market trends. They look at:
- Sale prices of similar properties
- Time on market
- Price trends over time
- Sales volume in the area
2. Property Characteristics
From property records, assessors consider:
- Square footage: Living area, finished basement, garage
- Lot size: Acreage or square footage of land
- Year built: Age affects value
- Number of bedrooms and bathrooms
- Property type: Single-family, condo, townhouse, etc.
- Features: Pool, deck, fireplace, etc.
3. Statistical Models
Assessors build regression models that predict property values based on these characteristics. For example, the model might determine that in your neighborhood:
- Each square foot adds $X to value
- Each bedroom adds $Y to value
- Properties built after 2010 are worth Z% more
- Properties with pools are worth $W more
These formulas are then applied to all properties in the area.
4. Location Factors
The model also considers:
- School district quality
- Neighborhood desirability
- Proximity to amenities
- Crime rates
- General market area trends
Pro Tip: The Model Doesn't Know Your Property
These statistical models work with averages and trends. They don't know that your roof needs replacement, your foundation has issues, or your property record says you have 3 bathrooms when you only have 2. That's why checking your property record is so important.
Reappraisal Cycles
Tennessee counties don't reassess properties every year. Instead, they conduct reappraisals every 4-6 years, during which all properties are reassessed based on current market conditions.
What Happens During Reappraisal
- All properties reassessed: Every property in the county gets a new value
- Based on current market: Values reflect recent sales and market trends
- Significant changes common: If the market has appreciated, assessments typically increase
- Appeal window opens: After reappraisal, you have a window to appeal (typically January through April)
Between Reappraisals
In non-reappraisal years, assessments typically stay the same unless:
- You make significant improvements (additions, major renovations)
- You file an appeal and get a reduction
- The assessor discovers an error in your property record
⚠️ Reappraisal Years Often Bring Big Increases
If your county just completed a reappraisal and your assessment jumped 30% or more, that's a red flag. Market values may have increased, but individual properties can still be over-assessed. This is often the best time to appeal.
Assessment Ratio (25% for Residential)
In Tennessee, you're not taxed on the full appraised value of your property. Instead, you're taxed on the assessed value, which is a percentage of the appraised value.
Residential Property: 25%
For residential property (your home), the assessment ratio is 25%. This means:
Assessment Calculation Example
- Appraised Value: $400,000 (what the assessor thinks your home is worth)
- Assessment Ratio: 25%
- Assessed Value: $100,000 (what you're taxed on)
- Tax Rate: Let's say $3.25 per $100 of assessed value
- Annual Property Tax: $100,000 × $3.25 / $100 = $3,250
Other Property Types
- Commercial/Industrial: 40% assessment ratio
- Farm/Land: 25% assessment ratio
- Personal Property: 30% assessment ratio
📊 How Property Taxes Are Calculated
Property Tax = Assessed Value × Tax Rate
Your assessed value is 25% of your appraised value. So if you can reduce your appraised value by $40,000 (from $400,000 to $360,000), your assessed value drops by $10,000 (from $100,000 to $90,000), saving you approximately $325 per year at a $3.25 tax rate.
Why Mass Appraisal Can Be Inaccurate
Mass appraisal is designed for efficiency and statistical accuracy across neighborhoods, but it can miss important details about individual properties:
1. No Physical Inspection
Assessors typically don't visit your property. They rely on property records, which may be outdated or incorrect. If your property has:
- Deferred maintenance (old roof, outdated systems)
- Foundation issues
- Water damage
- Functional obsolescence (outdated layout)
The assessor's model doesn't know about these issues.
2. Property Record Errors
Property records can contain errors that inflate your assessment:
- Wrong square footage (too high)
- Incorrect number of bedrooms or bathrooms
- Features you don't have (pool, finished basement, etc.)
- Wrong lot size
- Incorrect year built
3. Negative Location Factors
The model uses neighborhood averages, but your specific property might have issues the model doesn't account for:
- Traffic noise from busy road
- Commercial neighbors
- Power lines or cell towers
- Flood zone
- Railroad tracks nearby
- Poor drainage or flooding issues
4. Market Timing
During reappraisal years, assessors use recent sales data. But if the market has cooled since those sales, or if your property type isn't selling well, the assessment might be based on outdated market conditions.
5. Comparable Sales Issues
The model uses sales of "similar" properties, but:
- Properties might not be truly comparable
- Sales might include foreclosures or short sales (not arm's length)
- Recent sales might not reflect current market conditions
💡 This Is Why Appeals Exist
Mass appraisal is efficient and generally accurate, but it's not perfect. The appeal process exists specifically to correct individual inaccuracies. If your property has issues the model missed, or if there are errors in your property record, you have grounds for an appeal.
Property Record Cards
Your property record card (also called a property card or assessment card) is the assessor's official record of your property. It contains all the information the assessor uses to value your property.
What's on Your Property Record Card
- Property identification: Address, parcel number, owner name
- Physical characteristics: Square footage, lot size, year built
- Room counts: Bedrooms, bathrooms, half-baths
- Features: Garage, basement, pool, fireplace, etc.
- Condition/quality: Construction quality, condition rating
- Assessment history: Previous values, changes over time
How to Get Your Property Record Card
- Online: Most counties have online property search tools on the assessor's website
- In person: Visit your county assessor's office
- By phone: Call and request a copy
For Davidson County, visit padctn.org and search for your property by address.
Pro Tip: Check Your Property Record First
Before filing an appeal, always check your property record card. Errors in square footage, room counts, or features are the easiest issues to win appeals on. If your record says you have 2,500 sq ft but you actually have 2,200 sq ft, that's a clear error that will likely result in a reduction.
Common Errors in Assessments
Here are the most common errors that lead to over-assessments:
Wrong Square Footage Common
Property record shows more square footage than you actually have. This is often the easiest error to prove and win on.
Incorrect Room Counts Common
Record says you have 4 bedrooms when you have 3, or 3 bathrooms when you have 2.5. These errors significantly affect value.
Features You Don't Have
Record lists a pool, finished basement, or garage that doesn't exist. These add significant value incorrectly.
Wrong Lot Size
Record shows larger lot than you actually own, or includes land you don't have access to.
Incorrect Year Built
Record shows newer construction date, making your property appear more valuable than it is.
Condition Not Reflected
Record doesn't account for deferred maintenance, foundation issues, or other condition problems that reduce value.
How to Check If Your Assessment Is Fair
Here's how to determine if your assessment might be too high:
1. Check Your Property Record
Get your property record card and verify every detail:
- Measure your square footage (or get it from recent appraisals)
- Count bedrooms and bathrooms
- List all features (garage, basement, pool, etc.)
- Verify lot size
- Check year built
2. Research Comparable Sales
Find 3-5 similar properties that sold recently:
- Similar square footage (within 10-20%)
- Similar age and style
- Same neighborhood or comparable area
- Sold within past 6-12 months
- Arm's length transactions (not foreclosures)
If these properties sold for less than your assessed value, you likely have a case.
3. Consider Property Condition
Does your property have issues that reduce value but aren't reflected in the assessment?
- Deferred maintenance (old roof, outdated HVAC)
- Foundation or structural issues
- Functional obsolescence (outdated layout)
- Negative location factors
4. Compare to Market Value
Your assessment should reflect the market value of your property. If you recently had an appraisal (from a refinance or purchase), compare it to your assessed value. If the appraisal is significantly lower, you have grounds for an appeal.
💡 Quick Check: Get a Free Evaluation
Not sure if your assessment is fair? Get a free evaluation and we'll analyze your property against recent sales data to see if you have a case for an appeal.
Think Your Property Is Over-Assessed?
If you've found errors in your property record or comparable sales suggest your assessment is too high, you may have a strong case for an appeal. Get a free evaluation to see if your property qualifies.
Get Free EvaluationSee if your property is over-assessed. Takes 2 minutes. No obligation.
Frequently Asked Questions
How does Tennessee assess property values?
Tennessee uses mass appraisal techniques—statistical models that analyze sales data, property characteristics, and market trends to estimate values across entire neighborhoods. Assessors don't physically inspect every property; instead, they use computer models based on property records and recent sales.
What is the assessment ratio in Tennessee?
For residential property in Tennessee, the assessment ratio is 25%. This means your assessed value (what you're taxed on) is 25% of your appraised value. If your home is appraised at $400,000, your assessed value is $100,000.
How often does Tennessee reappraise properties?
Tennessee counties conduct reappraisals every 4-6 years, though some counties may do them more frequently. During reappraisal years, all properties are reassessed based on current market conditions, which often results in significant value increases.
Why might my property be over-assessed even if the neighborhood average is accurate?
Mass appraisal is designed to be accurate for neighborhoods overall, but individual properties can still be over-assessed. Your property might have condition issues, errors in the property record, negative location factors, or other problems that the statistical model didn't account for.
How do I get my property record card?
You can get your property record card online through your county assessor's website, in person at the assessor's office, or by calling and requesting a copy. For Davidson County, visit padctn.org and search for your property by address.
What should I do if I find errors in my property record?
If you find errors in your property record (wrong square footage, room counts, or features), you have strong grounds for an appeal. Document the errors with measurements, photos, or other evidence, and include this in your appeal. Property record errors are among the easiest issues to win appeals on.
Can I appeal my assessment every year?
Yes, Tennessee law allows you to appeal your property assessment every year during the informal review window (typically January through April). However, your evidence must support a lower value. If nothing has changed since last year and your assessment is fair, a new appeal may not be successful.