Definition · Staffing and agencies
Preferred Supplier List
Definition
Preferred supplier list (PSL) is the approved set of staffing agencies and recruitment vendors a company allows hiring managers to use, under pre-agreed terms and rates. It replaces ad hoc agency use with a controlled group of suppliers, often organized into tiers that receive requisitions in order of priority and performance.
Also called: PSL, Preferred vendor list, Approved supplier list, Supplier tiering
How a preferred supplier list works
Procurement or the contingent workforce team selects suppliers through an RFP, signs each one to a master service agreement with standard rates and fees, and publishes the list. Hiring managers can only engage suppliers on the list, and invoices from anyone else are rejected or escalated.
In larger programs, the PSL is administered through a vendor management system and often by a managed service provider. Requisitions are distributed to suppliers automatically according to rules, submittals are tracked, and performance data is collected for each supplier.
Supplier tiering
Most PSLs sort suppliers into tiers:
- Tier 1: two to four primary suppliers that get every requisition in their category first, usually with exclusivity for 24 to 72 hours.
- Tier 2: secondary suppliers that receive the requisition if Tier 1 cannot fill it in the window, or for specific geographies.
- Tier 3 or specialty: niche suppliers for hard-to-fill skills, diversity-owned suppliers or specific locations.
Tiering by category is common: one set of suppliers for light industrial, another for IT, another for clinical or contact center roles. A supplier earns a higher tier through performance, measured each quarter, and loses it the same way. Tiering gives strong agencies enough volume to invest in your account, which flat lists of 20 suppliers do not.
How many suppliers to include
Fewer than most companies think. With too many agencies, each gets a small share of requisitions, so none dedicates recruiters to the account, and candidates get submitted by three agencies for the same job, which creates ownership disputes. With too few, coverage gaps appear in specialized skills or new locations.
A practical range for a mid-size program is three to eight suppliers per job category, with a clear Tier 1. For a high-volume contact center program hiring a few hundred agents a quarter, two strong primary suppliers and one or two backups usually outperform a list of ten.
Measuring supplier performance
Review each supplier quarterly against the same scorecard:
- [Fill rate](/glossary/fill-rate/): share of requisitions filled.
- Time to submit and time to fill.
- Submittal-to-interview and interview-to-hire ratios, which show quality of candidates.
- Early turnover: workers who leave or are removed in the first 30 days.
- Compliance: background check completion, timesheet accuracy, invoicing errors.
- Rate compliance: bill rates and markups within the rate card.
Share the scorecard with suppliers. Agencies respond to clear data, and a supplier at the bottom of the scorecard should know why before it is moved down a tier.
Common mistakes
- Adding a supplier every time a hiring manager has a favorite recruiter, until the list is meaningless.
- Never removing poor performers.
- Letting managers bypass the PSL for 'urgent' roles, which become the norm.
- Setting rates so low that only the weakest agencies accept the terms.
- Ignoring direct hire: many PSLs cover temporary staffing but leave placement fees for permanent searches uncontrolled.
Frequently asked questions
What is a preferred supplier list?
An approved list of staffing agencies and recruitment vendors that hiring managers may use, each signed to standard terms, rates and fees.
What is a PSL in recruitment?
The same thing: a preferred supplier list of recruitment agencies, usually with agreed fees for permanent placements and rates for temporary workers.
What is supplier tiering?
Organizing suppliers into priority levels so requisitions go to top-performing Tier 1 suppliers first and are released to Tier 2 or specialty suppliers only if not filled within a set window.
How do you get on a company's preferred supplier list?
Usually by responding to an RFP when the company reviews its list, often every two to three years, or by filling a gap in a specialty or location the current suppliers cannot cover.
What is the difference between a PSL and an MSP?
A PSL is the list of approved suppliers. An MSP is a company that manages the contingent workforce program, often including running the PSL, distributing requisitions and tracking supplier performance.