Xactimate supplement guide.
A supplement is a revised estimate that adds or changes the scope of the original. Comparing the supplement to the original line by line is the fastest way to understand what changed and why.
A supplement updates the original estimate with new information.
As work progresses, the full scope often becomes clearer. A supplement captures additional activities, quantities, or code changes that were not in the first estimate.
Why supplements happen
- Hidden damage found after work begins.
- Original estimate used a code that does not match the existing finish.
- Quantity or geometry was measured differently on site.
- Building code or material requirements changed.
- Carrier requested additional documentation after review.
What a supplement should contain
- The original estimate reference number.
- A clear list of added or changed line items.
- Updated quantities and unit prices.
- Revised summary totals and loss recap.
- Notes or photos supporting the changes.
What typically changes between original and supplement.
Most supplements fall into a few predictable categories. Knowing them helps you read the comparison faster.
New line items
Activities that were not in the original estimate, such as additional repairs discovered after demolition.
Quantity increases
Rooms or measurements that were larger or more complex than originally estimated.
Code upgrades
Original code did not match the existing material or local code; upgraded to a more appropriate line item.
Price list updates
Supplement uses a newer or different price list that reflects current market pricing.
O&P corrections
Original applied overhead and profit differently than the scope of work justifies.
Coverage reallocation
Items moved from one coverage bucket to another based on new information.
How to build a defensible supplement record.
A strong supplement is documented line by line. The clearer the record, the faster the review.
- 1Save the original estimate as a separate PDF before writing the supplement.
- 2In the supplement, note which lines are new and which update existing lines.
- 3Keep photos and notes that explain why a change was made.
- 4Make sure the supplement totals reconcile to the original plus the change amount.
- 5Export the supplement in a format both sides can read without special software.
- 6Compare the original and supplement side by side before submission.
Let the numbers show what changed.
Estology reads the original estimate and the supplement, aligns the rooms and line items, and highlights every change. The result is a report both sides can inspect.
What the comparison shows
- New items added in the supplement.
- Items removed or changed from the original.
- Quantity and unit-price drift.
- Summary-level changes in O&P, tax, and depreciation.
- Reconciliation of the total change amount.
Why it matters
Supplement reviews often stall because the two sides are looking at different pages. A line-by-line comparison puts the same facts in front of both parties and lets the conversation focus on scope, not arithmetic.
Before you write the supplement, Estimate Review can score the original estimate, name what it left out, recommend the line item that covers each gap, and price that gap from the estimate's own measurements and unit prices, so the supplement starts from a figure you can defend line by line.
Compare an original estimate to its supplement.
Upload both PDFs and get a line-by-line report of every change. First comparison is free.