The Four-Flag Check: a collision estimate review checklist for every estimate stage

Who this is for

This checklist is for collision estimators, production managers and owners who want help catching what an estimate missed without handing the sheet to software. It goes with our short video on the Four-Flag Check and the longer page on collision estimate automation.

The rule from the video: think of it like a second estimator who can point but never holds the pen. You'd think automation should fill in the estimate for you, but a tool that quietly adds or removes a line isn't automating the estimate. It's writing it, and the person who signs has lost control of the document.

It matters more every quarter. CCC data reported by Autobody News shows calibrations on 35.6% of DRP estimates in Q3 2025, and 51.5% of calibrations appearing on supplements rather than the initial estimate. Every one of those is work found after the car was apart.

What you need first

• Access to OEM repair information. The I-CAR Repairability Technical Support portal links to what the vehicle maker says, including an OEM calibration requirements search, and your estimating platform may carry procedures too.
• Your photo set, named. Corners, sides, VIN plate, odometer, and teardown photos named by area so a flag can point at one.
• The insurer's written parts rules for your DRP programs, in one place.
• One person who owns the sheet. The estimator who signs.

The four flags

Each flag is a question the estimator would rather be asked at the desk than discover at the end of the job.

1. Missing line

The question: do the teardown photos or the notes support work that isn't on the sheet?

Check for: blend panels, one-time-use hardware, corrosion protection, and a scan after the repair. CCC data reported by Repairer Driven News found nearly 87% of repairable DRP appraisals included a diagnostic scan in Q1 2025, so a sheet without one should at least prompt a look.

Example flag (demo): "Teardown photo 7 shows blend work on the fender. Add a blend line?"

2. Hidden damage

The question: does a photo show a gap, ripple or misalignment that the sheet doesn't account for?

Check for: panel gaps that changed after teardown, ripples behind a bumper, brackets out of line, a support that isn't square. The point is to look before the panel goes back on.

Example flag (demo): "Photo 11: gap at the radiator support. Look before reassembly?"

3. OEM step

The question: does the manufacturer require a scan, a calibration or a replacement condition that the draft doesn't carry?

Check for: calibrations after removing a bumper, windshield or mirror; parts the maker says to replace rather than repair; required pre- and post-repair scans. This is the flag that keeps a shop out of real trouble, because it's about whether the repair is right, not just whether it's paid.

Example flag (demo): "OEM procedure lists a front radar calibration after bumper R&I. Not on the sheet."

4. Parts choice

The question: does an aftermarket or recycled part conflict with the vehicle's age, the OEM guidance or the insurer's own written rules?

Check for: sensor-bearing parts, safety parts, and programs whose rules name OEM parts for newer vehicles. Sometimes the shop wants that argument. If so, it should have it on purpose, with the reference in hand.

Example flag (demo): "Aftermarket headlamp selected. OEM guidance and the insurer's written rules point to OEM. Your call."

The rule that keeps it honest

A flag is a question, not an edit. Software, a checklist or a second estimator can raise a flag, attach the photo or the procedure, and wait. Only the estimator adds, removes or changes a line, and only the estimator signs. Frameworks for AI risk say the same thing in general terms: the NIST AI Risk Management Framework starts with Govern, which is about deciding who is accountable for an AI system and its outcomes.

The flags at each of the five estimate stages

Stage	Which flags matter most	What to check
1. Intake photos and pre-scan	Hidden damage	Missing angles, dark photos, no VIN plate or odometer, pre-scan codes saved to the right car
2. Initial estimate	Missing line, OEM step, parts choice	Draft against intake photos, pre-scan codes and the OEM procedure
3. Insurer review and appraisal	Parts choice, OEM step	Photos, part numbers and procedure references ready for each contested line
4. Supplement	Missing line, hidden damage, OEM step	Teardown evidence assembled the day it's found, the request's age visible
5. Final bill	Missing line	Labor done and never claimed, sublet invoices not on file, lines that differ from the approved version

The further down the stages you go, the narrower the automation and the wider the estimator's role. At stage 3 software can prepare the conversation with the appraiser; it can't have it.

How to run it on ten closed estimates

1. Pull ten closed repairs from the last two months, mixed by size.
2. For each, compare the first estimate with the final bill and list every line added later.
3. Tag each added line with the flag that would have caught it: missing line, hidden damage, OEM step or parts choice.
4. Note the stage where it was found and the stage where a flag could have raised it.
5. Count by flag. The flag with the most tags is where to start, by hand or with software.

This gives you your own baseline instead of a vendor's percentage, and it shows estimators the check is about catching work earlier, not second-guessing them.

Where RevvOS fits

RevvOS doesn't write estimates or claim ADAS calibration detection; that work lives in the estimating and insurance platforms that hold the procedure libraries. It reads the repair plan the shop is running and makes sure the calibration line, the sublet booking and the reassembly order are visible to the person who decides. For the work around the estimate, see auto body shop automation software, or book an assessment and bring ten closed estimates.