Tax Gap Detection
Tax Gap Detection compares this year's imagery with last year's and with your roll, and flags additions, pools and outbuildings that were never assessed. You get the parcels ranked for field verification.
The job today
Permits catch the work people told you about. The rest you find by driving a neighbourhood, following up a tip, or flipping through last flight's photos next to the record card. Appraisers get to the areas they know, so the same streets get looked at and the others wait.
Somebody adds a pool and a detached garage, nobody sees it, and the parcel sits on the roll as it was until the next time an appraiser happens down that road.
Comparison
Spot-checks and permits
Permits, tips and the neighbourhoods the field appraisers choose to cover.
With Tax Gap Detection
Every parcel in the jurisdiction is compared, year over year, so the whole roll gets a look.
Spot-checks and permits
An appraiser drives by, or compares old photos with the parcel record by eye.
With Tax Gap Detection
The two passes are compared and any new roofed area, pool or outbuilding is flagged where the roll has no match.
Still yours
Deciding whether a change is taxable in your jurisdiction.
Spot-checks and permits
The record card and the appraiser's memory of the property.
With Tax Gap Detection
Each flag comes with a before and an after crop, so you can see what changed between the two passes.
Spot-checks and permits
By route, by area, or by whoever complained.
With Tax Gap Detection
Flagged parcels are ranked by estimated added value, so the visits that matter most to the tax base come first.
Spot-checks and permits
Pull the permit file and look for the address.
With Tax Gap Detection
The flagged list is the thing you check against your permits, which narrows the search to parcels with visible change.
Still yours
Your permit data and what it means for a given parcel.
Spot-checks and permits
A field appraiser visits, measures and updates the record, and the notice goes out.
With Tax Gap Detection
The same, on a shorter list with the crop pair in the packet.
Still yours
The visit, the measurements, the value and the notice. A flag is a lead, not a finding.
What you get
01
Ranked list, by parcel ID
Every parcel where the imagery changed and the roll shows nothing to match, ranked by estimated added value. Comes once a year, before the visit season. It feeds the visit list.
Ledger rows: R04 Ordering the visit listR01 Deciding which parcels to look at
02
Before and after crop
One pair for each flag, from last year's pass and this year's, for the field packet. The appraiser can see the change before leaving the office.
Ledger rows: R03 Telling new from oldR06 Confirming and assessing
03
Table keyed on parcel ID
The list carries your parcel ID, so it joins to the GIS layer and to the CAMA record.
Ledger rows: R05 Checking permits
How it works
Send the boundary and the roll. We compare two annual passes against it, and return the flagged list and the crop pairs in time to plan the visits.
01
The jurisdiction boundary and a current extract of the roll, with parcel IDs.
02
This year's and last year's VHR imagery at 0.5 m or finer, satellite or aerial.
03
Changed ground is compared with what the roll says is on the parcel. Changes that match an assessed improvement drop out.
04
The flagged parcels ranked by estimated added value, with a before and after pair for each.
Limits
A field appraiser sees the inside of the property, the quality of the work and what is behind a fence. Imagery sees from above, once a year.
At 0.5 m a pixel is about 20 inches across. A pool, an addition or a garage shows. A small garden shed may show as change without telling you what it is. Interior work and anything the size of a few pixels is out of reach.
Dense tree cover and heavy shadow can hide a smaller addition. Those parcels can come back clean when something is there.
It runs once a year. It does not watch the roll between cycles or flag new work as it happens.
It means the imagery changed and the roll has no match. Whether the change is taxable, permitted or already assessed is for field verification to decide.
Who it's for
FAQ
No. It gives them a ranked list of parcels and the change images to take with them. The visit and the assessment are theirs.
No. It means the imagery changed in a way the roll doesn't match. A visit confirms what is there.
Pick a neighbourhood you already reconciled on the ground and ask us about running it as a trial. Then compare the flags with what your appraisers found.
Additions, pools and outbuildings visible from overhead. Interior renovations don't show.
Cross-checking against your permit data is part of scoping the job. It is not automatic.
The jurisdiction boundary and an extract of the roll with parcel IDs.
The list is keyed on your parcel ID, so it joins to the record. We don't write into your CAMA system.
Less well. Dense canopy and shadow can hide smaller additions, and we say so on the list.
Ownership and licence terms are agreed in writing when you get started. If your counsel needs them earlier, ask.
Price depends on the size of the jurisdiction and the imagery used. Tell us how many parcels you carry and we'll scope it.
Send us the boundary of the jurisdiction. We'll tell you what a full-roll pass would show.