An Xactimate supplement is a written request to change an estimate the carrier has already approved. It holds up when every added line states its reason, its measurement and the evidence behind it. This guide is for the contractor or estimator who prepares that request, and it gives a line sheet, a filled kitchen example and an order to send the file in.
What an Xactimate supplement is, and when one is needed
A supplement adds to, corrects or re-prices an estimate that already exists. It is not a new claim for a new loss. It answers one question: what changed since the approved estimate, and how do you know?
The word is not used the same way everywhere. In the software publisher's payment tracker help for its contents product, a supplement is a scope change made after the first actual cash value payment, and a change made before that payment is a correction. Use the word your carrier's letter or portal uses.
Write one when the approved estimate and the work in front of you disagree. A line the carrier reviewed and declined, where no new fact has appeared, is a dispute. That follows a different path, touched on in the last section.
Start from a copy of the estimate you are amending, so the price list and the original lines stay as the carrier saw them. How a claim estimate is written shows what a full file contains. Where this guide and your policy or state law differ, the policy and the law control.
Why supplements happen: scope, hidden damage, code, price list
Sort every line into one of five reasons. The table pairs each reason with what to attach.
Reason | What happened | Attach |
|---|---|---|
Scope missed | Visible at the first inspection, but no line carries it. | Dated photo of the item in place, plus its measurement |
Damage found later | Demolition, an opening or the next day's readings show more than the first look. | Dated photos at the opening with a scale reference, and readings by day |
Quantity error | The line is right and its quantity is wrong. | Sketch or measurement page showing both numbers |
Code-required item | The adopted building code or permit adds work. | The adopted section and any local amendment |
Price list | The list on the estimate is not the one the carrier's instruction, program or pricing date calls for. | The estimate header and the document naming the list |
The first three are field facts, so photos and sketches prove them. The last two are rules, so a document proves them. Code work is also a policy question. California's residential property claims guide describes ordinance or law coverage as an endorsement, and says that without it the policyholder may pay for code upgrades. A code item can be correct and still not be covered, because whether code upgrades are covered, and up to what limit, is in the policy.
Unit prices normally come from the price list assigned to the claim. In Xactimate online, as of this writing, you set or change that list under Claim Info, then Parameters, per the publisher's price list help. Treat a list change as its own decision, not one more row.
The five parts of every supplement line
A reviewer reads a line cold. Give each line five parts:
The item in plain words, with quantity and unit.
The reason, from the table above.
The measurement: the arithmetic or sketch page behind the quantity.
The evidence reference: photo numbers, reading dates, invoice numbers.
The rule, only if one applies: a code section, product instruction or policy term.
Before you send, compare each new line with the approved estimate. A line that repeats work an existing line already includes reads as double counting.
Xactimate can hold the proof on the line. In the desktop product, as of this writing, F9 opens a line's notes, and a note can be text, an image, a sound file or a document, per the publisher's line notes help. That page does not say whether notes print on exported reports, so keep the same references in the line sheet. Keep notes to what the item is for and where the proof is.
Document in an order a reviewer can follow
Put the shortest documents first and the heaviest last, so a reviewer can follow each line and go to the proof only where a line needs it. Build the file in this order.
1. Cover note, one screen. Claim number, the estimate version you are amending, the price list name and date from its header, and a count of changed lines by reason.
2. Line sheet. One row per changed line, with the five parts.
3. Revised estimate. The file the reviewer compares with the approved one.
4. Sketch with dimensions. Needed for every quantity line.
5. Photos, numbered. One wide shot of the area, one of the damage, and one close shot with a tape or ruler in frame.
6. Logs and readings. The drying log: moisture map, readings by date, where each unit sat and how many days it ran.
7. Rule pages. The adopted code section with local amendments, or the manufacturer's instruction page.
8. Invoices and receipts. Permit receipts, disposal slips and subcontractor invoices for work already done.
9. Notice record. When, how and by whom the carrier was told about added damage.
Number every page and photo, and match the numbers to the evidence column. A reference nobody can find proves nothing. If the carrier's letter or portal asks for a different order or format, follow that first. Use this order when nobody has told you.
A filled line sheet for a water-damaged kitchen
A bulk request says "added drywall, flooring and drying, see attached." A line request names the item, the reason, the quantity and the proof.
The sheet below has six lines for an invented kitchen with a failed supply line. The room is 12 ft by 14 ft, with a 4 ft by 7 ft pantry alcove and a 3 ft doorway in the east wall. Both the north and east walls are wet. Base cabinets run along the 12 ft north wall with a 2 ft refrigerator gap, and the soft subfloor is a 4 ft by 6 ft patch under the sink. One supplement amends one estimate on one price list, so the List column repeats.
Line | Reason | Evidence | Measurement | Code | List | Status |
|---|---|---|---|---|---|---|
1. Remove wet drywall to 4 ft: 92 SF (estimate had 46) | Damage found later | Photos 8-10; readings to 4 ft | 12 + (14 - 3) = 23 LF; 23 x 4 = 92; 92 - 46 = 46 SF added | None | Same | Ready |
2. Replace damaged subfloor: 24 SF | Damage found later | Photos 14-16, vinyl removed | 4 x 6 = 24 SF | None | Same | Ready |
3. Floor covering: 196 SF (estimate had 168) | Quantity error | Sketch page 2, alcove | 12 x 14 = 168; 4 x 7 = 28; 168 + 28 = 196; add 28 SF | None | Same | Ready |
4. Detach and reset base cabinets: 10 LF | Scope missed | Photos 5-7, cabinets against wet wall | 12 - 2 (refrigerator gap) = 10 LF | None | Same | Ready |
5. Replace four counter receptacles with the type the adopted code requires there: 4 EA | Code-required item | Photos 18-19, opened wall | Count: 4 | [Adopted electrical code section] | Same | Needs section |
6. Drying equipment, 3 more days: air movers and dehumidifier | Damage found later | Daily readings, days 4-6 | Air movers: 2 x 3 days = 6 unit-days; dehumidifier: 1 x 3 days = 3 unit-days; two lines, each priced on its own | None | Same | Waiting on day 6 log |
Read line 1 left to right. The estimate carried 46 SF, readings at demolition reached 4 ft, and the new 92 SF comes from the same 23 LF of wall. A photo or a tape can check each number. Lines 5 and 6 are not ready, so hold them out of the submission until the code section and the day 6 log are in hand.
Line 5 is a code item only to the extent that the code requires a different type of receptacle than the one that was there. Swapping a wet receptacle for the same type is damage found later. The code cell is a placeholder on purpose, because adopted editions and local amendments differ. Paste the section and any amendment from your own jurisdiction.
Here "estimate" means a line-item repair document that a carrier reads, not a bid. The estimate versus proposal post separates the other senses of the word. If you build the sheet in a spreadsheet, an estimate layout line by line shows how each row keeps its quantity and unit.
The example is simplified. It has no prices, category or selector codes, tax, overhead and profit, or depreciation; a real file has all of them.
A supplement backlog is a writing problem more than a persuasion problem, and handing the line-by-line write-up to an outside estimate writer leaves you time to run the jobs. Takeoff Services LLC sells that write-up, so weigh the point accordingly. The sheet and the checklist work without it.
One supplement or several: timing the submission
Hold small items until demolition shows the full scope, then send one complete supplement. Choose the timing this way:
Send now if work cannot continue without the item, or a notice date is near.
Otherwise wait for demolition to finish, then send one supplement.
At completion, send a short final supplement for quantities that changed in the field.
Give the policyholder your findings and dated photos the day you find added damage, so they can report it. Whether and how to report is for the policyholder and the policy. California's guide tells the policyholder to notify the insurer immediately. It says a claim can usually be reopened and gives no deadline for that, but your policy and state law can still set one.
A state can put notice limits in a statute. Florida's notice statute bars an initial or reopened claim unless notice comes within 1 year after the date of loss, and a supplemental claim unless it comes within 18 months, in accordance with the policy's terms. It defines a supplemental claim as added loss from the same peril the insurer already adjusted, or repair costs incurred under an open claim with timely notice previously given.
The clock counts from the date of loss, not the first estimate. Take an illustrative loss on September 12, 2026. The 1-year date is September 12, 2027, and the 18-month date is March 12, 2028. The example is simplified. For weather events the statute fixes the date of loss itself (landfall for a hurricane, NOAA verification for other weather), and it pauses the limits for certain military deployments. That is one state's 2026 text, so check the current statute and your policy before you rely on any date.
Roofing supplement items to check against plans and photos
A roofing supplement uses the same sheet. Most lines are lengths and counts you can compute from the roof, so compute them before you read the carrier's scope. Back the lengths with a tape sketch or an aerial measurement report, and keep the arithmetic beside them. Take an invented gable roof: 40 ft by 30 ft, ridge along the long side, a 1 ft overhang at eaves and rakes, and a 6 in 12 pitch. Each figure below is rounded as printed, and the next step uses the printed figure.
Step | Arithmetic | Result |
|---|---|---|
Slope factor | Square root of 1 + (6/12) squared | 1.118 |
Eave-to-ridge run | 15 + 1 overhang | 16 ft |
Sloped face | 16 x 1.118 | 17.89 ft |
Ridge length | 40 + 1 + 1 rake overhang | 42 ft |
Roof area | 2 x 42 x 17.89 | 1,502.8 SF, or 15.03 squares |
Area from the plan alone | 2 x 42 x 16 | 1,344 SF, or 13.44 squares, which is 1.59 squares short |
The items then follow from those lengths and from counts at the roof.
Item | Quantity from this roof | Proof | Rule to attach |
|---|---|---|---|
Drip edge | 84 LF eaves + 71.6 LF rakes = 155.6 LF | Photos of bare eave and rake edges | Adopted code section, or product instruction |
Starter course | 84 LF along the eaves | Eave photo with the edge length noted | Product installation page |
Ridge cap | 42 LF | Ridge photo | Product installation page |
Underlayment | 15.03 squares of roof area, waste shown separately | Photo of the bare deck at tear-off | Adopted code section or product installation page |
Pipe flashings | 2 EA, one per penetration (illustrative count) | One photo per penetration | Product installation page |
Extra layers | Count at the cut edge | Close photo of the edge showing each layer | Local tear-off rule or code section, if one applies |
Deck replacement | Sheets of 32 SF, counted | Each bad sheet numbered and outlined at tear-off, in dated photos | None; the photos are the proof |
Put drip edge or an ice barrier on the sheet where the existing roof had it, or where the adopted code or the manufacturer calls for it, and say which reason applies. South Carolina's regulation 8-1228, for example, calls for drip edge at the eaves and rake edges of asphalt shingle roofs where the manufacturer requires it. Another state may read differently, so cite the text your jurisdiction has adopted now, not a model code. Show waste as its own stated percent, because waste folded into a quantity no longer matches the measurement.
Measuring a roof or room from plans covers the method. This example is simplified: one pair of planes, no hips or valleys, and an invented flashing count.
Where an estimate writer stops: no claim negotiation
The estimate writer's job ends at the document.
Takeoff Services LLC works inside this box. Its supplement write-up is the document only, and it does not contact adjusters or negotiate.
State law draws its own line for contractors. Florida's section 489.147 bars a contractor from interpreting policy provisions, advising the insured on coverages or duties, or adjusting the claim for the insured, unless the contractor holds a public adjuster license. That is one state's rule, not a map. Read your state's current text.
A dispute belongs to the policyholder, not the writer. California's guide sends a policyholder who disputes an offer to the insurer's claims manager first, then to the state Department of Insurance, with an attorney as a further step.
This post explains how the documents and rules work. It is not legal advice, and your state law, policy and contract control.
Other specialty scopes share the trait that someone else's document sets the rules. Prevailing wage, schedule and steel scopes are set side by side with this one. The prevailing wage version, where a wage determination sets the rates, is priced in a classification-by-classification labor build-up. To weigh who should write supplements, a scorecard for any outside estimator scores every provider on the same criteria, and the answer can be to keep the work in house.
Whoever writes it, an Xactimate supplement is finished when every line has its reason, its measurement and its proof.
Frequently asked questions
What is an Xactimate supplement?
A written request to add to or correct an estimate the carrier already approved. It lists each changed line with its reason, measurement and evidence, and covers missed scope, damage found later, wrong quantities and code-required work. It is not a claim for a new loss, and the carrier decides what it pays.
What documentation supports an insurance claim supplement?
Dated, numbered photos tied to each line, a sketch with dimensions for every quantity, and daily readings where drying is involved. Add the code or product page where a rule applies, receipts for work already done, and a cover note naming the estimate version and price list. The policy and carrier instructions control.
When should a contractor send a supplement?
Send an Xactimate supplement once demolition shows the full scope, unless an item stops the job or a notice window is close. Show the policyholder added damage the day you find it, with the photos; reporting it to the carrier is the policyholder's step. Deadlines come from state law and the policy, so read both before you wait.
Can an estimate writer negotiate with the adjuster?
An estimate writer produces the document: lines, measurements, notes and the line sheet. Negotiating, arguing coverage and advising on policy terms belong to the policyholder, the carrier and anyone licensed to act for the policyholder. Some states also restrict what contractors may do in a claim.
What is a roofing supplement?
A roofing supplement is the same request applied to a roof estimate. Most lines are lengths and counts you can compute from the roof, such as drip edge, starter course, ridge cap and deck sheets. Each needs a photo and, where one applies, the adopted code section or the product instruction.
Can you send more than one supplement on a claim?
Often yes, but the policy and the carrier's instructions control. Most files go better as one complete Xactimate supplement after demolition, plus a short final one for field changes at completion. Send earlier when an item stops the job or a notice date is close.
