FAR 4.1603—Procedures.
Plain-English Summary
FAR 4.1603 explains how to build and use procurement instrument identifiers (PIIDs) and supplementary PIIDs so federal contracts, orders, solicitations, agreements, and related actions can be uniquely tracked across government systems. It covers the required PIID structure, including the 13- to 17-character format, the prohibition on special characters, the use of the issuing office’s Activity Address Code (AAC) in positions 1 through 6, the fiscal year in positions 7 and 8, the instrument-type code in position 9, and the agency-assigned serial number in positions 10 through 17. It also covers the separate supplementary PIID used for amendments to solicitations and modifications to contracts, orders, and agreements, including the numbering rules for solicitation amendments and for modifications, the office identifier in the first position of the supplementary PIID, and the sequencing rules for issuing those numbers. In practice, this section exists to ensure every procurement action is uniquely identified, consistently reported, and traceable in procurement databases and contract files. For contractors and contracting offices, the rule matters because incorrect PIIDs or modification numbers can cause reporting errors, award-document mismatches, payment or administration confusion, and data integrity problems in systems such as FPDS and agency contract writing systems.
Key Rules
Use a 13-17 character PIID
Every PIID must contain 13 to 17 alpha and/or numeric characters. Special characters such as hyphens, dashes, and spaces are not allowed.
Identify the issuing office
Positions 1 through 6 must be the AAC assigned to the office issuing the instrument. Agencies must use the correct AAC for the issuing office, not a generic or parent-office code unless that is the actual issuing office code.
Show the fiscal year
Positions 7 and 8 are the last two digits of the fiscal year in which the procurement instrument is issued or awarded. Use the date the action is signed, not a later effective date if those dates differ.
Use the correct instrument code
Position 9 must contain the proper uppercase letter for the type of instrument, such as C for contracts, D for indefinite-delivery contracts, F for task or delivery orders, P for purchase orders, Q for RFQs, R for RFPs, and L for lease agreements. Some letters are reserved or prohibited, and agencies may use certain department-designated letters only if applied consistently across the department or agency.
Assign the serial number consistently
Positions 10 through 17 contain the agency-assigned number. Agencies may use a minimum of four and a maximum of eight characters, but the chosen length must be used agency-wide, and leading or trailing zeroes may not be added just to fill out the maximum length.
Use separate series when needed
Agencies may use separate numbering series for different instrument types and may reserve blocks of numbers or alphanumeric ranges for components. This supports internal control and avoids duplicate PIIDs.
Report amendments separately
The supplementary PIID is a separate data element used with, not appended to, the PIID to identify amendments to solicitations. Solicitation amendments are numbered sequentially with a four-position numeric serial number beginning with 0001.
Number modifications by office
Modifications to contracts, orders, and agreements use a six-position alpha/numeric supplementary PIID. Position 1 identifies the issuing office: P for the procuring contracting office and A for the contract administration office if different from the procuring office. Positions 2 through 6 may be alpha, numeric, or a combination under agency procedures.
Issue modification numbers in sequence
Each authorized office must assign supplementary modification numbers sequentially unless agency procedures say otherwise. The number should not be assigned until it is determined that a modification will actually be issued.
Responsibilities
Contracting Officer / Procuring Contracting Office
Assign the correct PIID structure for awards and other instruments issued by the office, including the AAC, fiscal year, instrument code, and serial number. For modifications issued by the procuring contracting office, use the supplementary PIID with position 1 set to P and assign numbers sequentially.
Contract Administration Office
When the contract administration office issues a modification instead of the procuring contracting office, use supplementary PIID position 1 set to A and follow agency procedures for the remaining positions and sequencing.
Agency / Department
Establish and enforce agency-wide PIID numbering policies, including the number of characters used in positions 10 through 17, any separate numbering series, reserved blocks, and any department-authorized use of certain instrument letters. Ensure the correct AACs are assigned and maintained.
System Administrators / Contract Writing System Owners
Configure systems to accept the required PIID and supplementary PIID formats, prevent prohibited special characters, preserve agency-wide numbering conventions, and support accurate reporting and data transmission without padding with unnecessary zeroes.
Contracting Staff / Data Entry Personnel
Enter PIIDs and supplementary PIIDs exactly as required, use the correct instrument code, avoid assigning modification numbers before a modification is actually authorized, and ensure amendments and modifications are numbered in the proper sequence.
Practical Implications
A wrong PIID can break downstream reporting and make the award or modification hard to find in procurement systems, so accuracy at creation matters as much as the contract terms themselves.
The fiscal year in the PIID is based on the signature/award date, not the effective date, which is a common source of errors when actions are backdated or made effective later.
Agencies must be consistent about the length of the serial number portion; mixing four-, six-, and eight-character formats within the same agency can create duplicate or noncompliant identifiers.
Modification numbers are not supposed to be pre-assigned casually. If a modification is never issued, the number should not have been consumed, because gaps and premature assignment can complicate audit trails.
Contractors should verify that the PIID and any modification/supplementary PIID on the award document match the system record exactly, since mismatches can cause invoicing, administration, or closeout problems.
Official Regulatory Text
(a) Elements of a PIID . The PIID consists of a combination of thirteen to seventeen alpha and/or numeric characters sequenced to convey certain information. Do not use special characters (such as hyphens, dashes, or spaces). (1) Positions 1 through 6 . The first six positions identify the department/agency and office issuing the instrument. Use the AAC assigned to the issuing office for positions 1 through 6. Civilian agency points of contact for obtaining an AAC are on the AAC Contact list maintained by the General Services Administration and can be found at https://community.max.gov/x/24foL . For Department of Defense (DoD) inquiries, contact the service/agency Central Service Point or DoD AAC Monitor, or if unknown, email DODAADHQ@DLA.MIL for assistance. (2) Positions 7 through 8 . The seventh and eighth positions are the last two digits of the fiscal year in which the procurement instrument is issued or awarded. This is the date the action is signed, not the effective date if the effective date is different. (3) Position 9 . Indicate the type of instrument by entering one of the following upper case letters in position nine. Departments and independent agencies may assign those letters identified for department use below in accordance with their agency policy; however, any use must be applied to the entire department or agency. Instrument Letter designation (i) Blanket purchase agreements A (ii) invitations for bids B (iii)Contracts of all types except indefinite-delivery contracts (see subpart 16.5 ) C (iv) Indefinite-delivery contracts (including Federal Supply Schedules, Governmentwide acquisition contracts (GWACs), and multi-agency contracts) D (v) Reserved for future Federal Governmentwide use E (vi) Task orders, delivery orders or calls under– Indefinite-delivery contracts (including Federal Supply Schedules, Governmentwide acquisition contracts (GWACs), and multi-agency contracts); Blanket purchase agreements; or Basic ordering agreements F (vii) Basic ordering agreements. G (viii) Agreements, including basic agreements and loan agreements, but excluding blanket purchase agreements, basic ordering agreements, and leases. Do not use this code for contracts or agreements with provisions for orders or calls H (ix) Do not use this letter I (x) Reserved for future Federal Governmentwide use J (xi) Reserved for departmental or agency use K (xii) Lease agreements L (xiii) Reserved for departmental or agency use M (xiv) Reserved for departmental or agency use N (xv) Do not use this letter O (xvi) Purchase orders (assign V if numbering capacity of P is exhausted during a fiscal year) P (xvii) Requests for quotations (assign U if numbering capacity of Q is exhausted during a fiscal year) Q (xviii) Requests for proposals R (xix) Reserved for departmental or agency use S (xx) Reserved for departmental or agency use T (xxi) See Q, requests for quotations U (xxii) See P, purchase orders V (xxiii) Reserved for future Federal Governmentwide use W (xxiv) Reserved for future Federal Governmentwide use X (xxv) Imprest fund Y (xxvi) Reserved for future Federal Governmentwide use Z (4) Positions 10 through 17. Enter the number assigned by the issuing agency in these positions. Agencies may choose a minimum of four characters up to a maximum of eight characters to be used, but the same number of characters must be used agency-wide. If a number less than the maximum is used, do not use leading or trailing zeroes to make it equal the maximum in any system or data transmission. A separate series of numbers may be used for any type of instrument listed in paragraph (a)(3) of this section. An agency may reserve blocks of numbers or alpha-numeric numbers for use by its various components. (5) Illustration of PIID. The following illustrates a properly configured PIID using four characters in the final positions: (b) Elements of a supplementary PIID . Use the supplementary PIID to identify amendments to solicitations and modifications to contracts, orders, and agreements. The supplementary PIID is reported as a separate data element used in conjunction with, but not appended to, the PIID. (1) Amendments to solicitations. Number amendments to solicitations sequentially using a four position numeric serial number added to the 13-17 character PIID beginning with 0001. (2) Modifications to contracts, orders, and agreements. Number modifications to contracts, orders, and agreements using a six position alpha or numeric, or a combination thereof, added to the 13-17 character PIID. For example, a modification could be numbered P00001. This would be added to the end of the 13-17 character PIID illustrated in (a)(5) of this section. (i) Position 1. Identify the office issuing the modification. The letter P shall be designated for modifications issued by the procuring contracting office. The letter A shall be used for modifications issued by the contract administration office (if other than the procuring contracting office). (ii) Positions 2 through 6. These positions may be alpha, numeric, or a combination thereof, in accordance with agency procedures. (iii) Each office authorized to issue modifications shall assign the supplementary identification numbers in sequence (unless provided otherwise in agency procedures). Do not assign the numbers until it has been determined that a modification is to be issued.