FAR 4.1006—Modifications.
Plain-English Summary
FAR 4.1006 addresses how to identify and reference changes made through contract or procurement instrument modifications. It covers two related topics: when a modification adds a new item, such as an increased quantity, and when a modification affects existing line items. Its purpose is to keep the procurement record clear, traceable, and consistent so that every change can be tied to the correct line item in the contract file, invoicing system, and property/accounting records. In practice, this section helps prevent confusion over what was added versus what was changed, which is important for administration, payment, auditability, and later disputes. It also supports accurate line-item management across the life of the instrument by requiring a new line item number for newly added items and a direct reference to existing line items when those items are being modified.
Key Rules
Assign new item numbers
When a modification adds a new item to the procurement instrument, the new item must receive a new line item number. This applies to additions such as increased quantities that are treated as new items rather than changes to an existing item.
Reference affected line items
If the modification changes existing line items, the modification must identify and refer to those specific items. The change should be tied to the original line item numbers so the record clearly shows what was altered.
Responsibilities
Contracting Officer
Ensure modifications are properly structured and that any newly added item is assigned a new line item number. When modifying existing items, clearly reference the affected line items in the modification document.
Contractor
Review modifications to confirm that new items are separately numbered and that changes to existing items are correctly tied to the original line items. Raise questions if the modification does not clearly identify the affected items.
Agency/Contract Administration Staff
Maintain accurate procurement records and line-item tracking so modifications are reflected correctly in contract files, accounting systems, and related administrative records.
Practical Implications
This rule keeps contract changes traceable, which matters for payment, audit, and closeout.
A common mistake is treating a newly added item as a change to an old line item, which can create confusion in billing and reporting.
Another pitfall is failing to identify the exact existing line items affected by a modification, making it hard to tell what was changed.
Clear line-item numbering helps avoid disputes over scope, quantity, and pricing because the record shows whether something was added or merely adjusted.
Contracting personnel should check that modification language matches the line-item structure used in the contract and in downstream systems.
Official Regulatory Text
(a) When a new item (such as an increased quantity) is added to the procurement instrument, assign a new line item number. (b) If the modification relates to existing line items, the modification shall refer to those items.