County assessments of improved homes are often roughly right. Assessments of vacant land are frequently not, and the reason is structural rather than carelessness on anyone’s part.
Why mass appraisal struggles with land
Counties value tens of thousands of parcels at once using models trained on property characteristics and recent sales. That approach works reasonably well for houses in a subdivision, where properties are similar and sales are frequent. It works badly for land, for four reasons:
- Land sales are infrequent. A model needs comparable transactions to learn from. In many areas there are only a handful of land sales a year.
- Parcels differ enormously. Two five-acre tracts can have completely different value depending on zoning, access, utilities and topography. A model working from acreage and a location code sees them as near-identical.
- The characteristics that drive land value are not in the tax record. Whether sewer is available at the street, whether there is legal access, how much of the parcel is floodplain. None of that is a field in the property record.
- Nobody visited. A parcel that is half unusable due to slope looks the same on paper as one that is flat and dry.
Which direction the error goes
Both, and that is the point worth understanding.
Over-assessment usually happens when a model applies a per-acre rate derived from developable land to a parcel that is heavily constrained. You pay tax each year on value the parcel does not have.
Under-assessment happens when land carrying entitlements or utilities gets valued like raw acreage. That feels like good news until you try to use the assessment as evidence of value in an estate or a divorce and find it is a fraction of the real figure.
This is why a low assessment is not evidence your land is worth little, and a high one is not evidence it is worth a lot. The assessment is an estimate produced for taxation, not an opinion of market value for your specific parcel.
What an appeal needs
If the assessment is too high, an appeal contests the county’s value. For land, the evidence that carries weight is specific:
- An independent appraisal with an effective date of January 1 of the tax year, which is Georgia’s assessment date.
- Documentation of constraints: floodplain mapping, a survey showing usable area, evidence of an access problem, a failed percolation test.
- Corrections to the property record, where acreage or zoning is recorded wrong. This is more common on land than on houses.
- Comparable land sales, adjusted properly. An unadjusted list of cheaper nearby parcels is easy for a county representative to take apart.
Deadlines run from the date on your annual notice of assessment and change year to year and county to county. Go by your own notice.
Whether it is worth appealing
The saving is the reduction in assessed value multiplied by your millage rate. On a modest parcel with a small over-assessment, the arithmetic may not justify the cost of the evidence, and we will say so before you spend anything.
Where it does tend to pay is a parcel materially over-assessed relative to what it can actually be used for, particularly where the constraint is documentable. Those cases are common precisely because the county’s model cannot see the constraint.
Our property tax appeal page covers the appeal process across Metro Atlanta counties, and the land appraisal page covers how vacant parcels are valued.
