You call a company about a role they just posted, and you get "we have a PSL." The question is what that sentence actually means, because it is used to mean three different things and only one of them is a contract.
A preferred supplier list, PSL, is a procurement arrangement: a named set of agencies a buyer has appointed for a fixed term, with hiring managers directed to brief only those agencies for the duration. It is a contract with a start date, an end date and a review window, and the published ones run two to four years. That matters more than whether the door is open, because it tells you when the door opens, and it means the live job posting in front of you is not the event that decides anything.
What a preferred supplier list actually is, and how long they run
Public-sector buyers publish their supplier arrangements, which makes them the only place to read real terms rather than descriptions of terms. Four of them, with what each one published.
The UK's national framework for non-clinical staffing, RM6277, runs from 25 April 2023 to 24 April 2027, holds 169 suppliers across seven lots, and is closed mid-term. Just under four years, and no route in until it retenders.
South East Coast Ambulance Service NHS Foundation Trust awarded its recruitment agency PSL from 17 October 2025 to 16 October 2028, with an option to extend a further year. Two lots, roughly ten agencies each, and a supplier may bid for and be awarded only one lot.
The General Medical Council's PSL for IS roles ran two years, from March 2020 to March 2022, with three named suppliers: Experis UK, Robert Walters and Reed Specialist Recruitment. Three agencies for a national regulator's technology hiring, for two years.
Activate Learning, a further education college group, is the only one of the four that publishes its review cadence: "Our PSL is reviewed annually, typically between January and March." It also publishes the rule that governs off-list approaches, in one sentence: "Only agencies formally appointed to the PSL are permitted to support recruitment, unless a specific, formally approved exception is in place."
Four buyers, four different terms. There is no standard PSL length, because it is set contract by contract. What is consistent is the shape: a fixed term, a defined set of suppliers, and a moment when the list reopens that has nothing to do with when a role goes live.
Why buyers run a closed list
It is worth knowing what the structure is for, because it explains why an argument about your fill rate does not move it.
The NHS Workforce Alliance makes the buyer's case directly. Framework terms "protect your trust against excess transfer fees, extended hire periods and other hidden charges." Pricing "is fully transparent and aligns to national pay scales." And framework owners "conduct independent audits of agencies to verify workers meet NHS employment standards," with agencies "potentially suspended if audits reveal compliance failures."
In the NHS framework's own account, then, the list exists to cap rates, standardise terms and shift compliance risk onto an audited supplier. That is one buyer type's stated rationale rather than a general theory of supplier lists, and the other three buyers above publish no rationale at all. It is still the clearest statement available of what the structure is for, and it explains why a new agency arriving with a better candidate is offering something the structure was not built to buy. The person you are talking to may agree with you entirely and still have no authority to act, which is the part that reads as a brush-off and usually is not one.
RPO, and who owns the requisition
Recruitment process outsourcing is a different animal from a supplier list, and the difference is who runs the process rather than who is allowed to pitch into it.
The industry body's own definition is precise. The Recruitment Process Outsourcing Association describes RPO as an arrangement where "an employer transfers all or part of its recruitment processes to an external service provider," and where that provider "assume[s] ownership of the design and management of the recruitment process and the responsibility of results." The RPOA explicitly distinguishes this from "staffing companies and contingent/retained search providers."
Read that ownership language against what you do when you see a posting. The hiring manager whose name is on the requisition is not the person who decides how it gets filled. Agencies do still work underneath RPO contracts, and HRO Today describes the mechanism plainly: "management of other vendors such as staffing and temp agencies is handled by the RPO vendor." You are a subcontractor to the provider rather than a supplier to the employer, and the conversation that gets you there is with the provider.
Two honest limits on what is known here. That HRO Today piece also gives typical RPO deal lengths and values, and its own market figures date to 2006 and 2007, so it describes deal structure rather than current benchmarks. And the one current analyst report on the RPO market, Staffing Industry Analysts' 2025 global landscape study, is behind a membership paywall. No current, non-vendor, publicly readable source on typical RPO contract length turned up in this research.
Internal talent acquisition, and what is genuinely not known
The third structure is the simplest to describe and the hardest to size. A company with a staffed internal talent acquisition function fills roles with its own recruiters and uses agencies for the exceptions.
What is knowable is the capacity. SHRM, citing ADP Research Institute payroll analysis across more than 25 million employees, puts typical HR staffing at 1.5 to 4.5 people per 100 employees, averaging 1.7, with recruiters the largest share of that. So a 400-person company has perhaps seven HR staff in total, and some fraction of those are recruiters. That is the size of the function you are competing with, and it is small enough that specialist and hard-to-fill roles routinely fall outside what it can cover.
What is not knowable is how much hiring that function actually absorbs. A REC-commissioned survey of 234 employers, run by Whitestone Insight and published in June 2025, found 42 percent trust a private recruitment agency most to find the right worker against 26 percent for in-house personnel, and REC is the recruitment industry's own trade body. Pointing the other way, Personnel Today reported in August 2026 on a vendor survey claiming 78 percent of companies now hire primarily direct, with no sample size disclosed.
No current figure from a party without a position in that argument appears to exist in the public record, which is worth knowing the next time someone quotes you one.
What each of the three means for the posting in front of you
The three structures fail differently, and the practical read on each is different.
A PSL company is reachable on procurement's calendar. The list has an expiry date, and one of the four buyers above also publishes an annual review window: Activate Learning's runs January to March. Whether any given buyer reviews between retenders is something you find out by asking or by reading the notice. That is a diary entry, not a call sheet, and the work that gets you onto the list is a supplier application rather than a pitch about a candidate. The exception route exists and is formal, which means it requires someone inside to sponsor it through an approval, not to take your call.
An RPO company is reachable through the provider. The employer has contracted out the decision, so the relationship you need is with a firm whose name is not on the job posting. Working out who runs a given company's process is a research task you do once per account, and it is a better use of an hour than five calls into a hiring manager who cannot act.
A company with a staffed internal TA function is reachable on the exceptions: the roles that stay open, the searches that fail, the niches their recruiters do not cover. That means the posting worth calling about is usually not the newest one.
In all three cases the requisition is real. The urgency you read into a fresh posting is the part that is false, because the timing that decides whether you can win the work is set somewhere else entirely and was set before the role was posted.
That is a separate failure mode from the one where the posting was never real hiring activity to begin with. Those have their own signals, and we covered them in how to spot a ghost job. A posting can pass every authenticity check in that piece and still be closed to you, which is why the two checks are worth running as separate questions.
What the practitioners who get onto lists say it takes
Agencies do get onto preferred supplier lists, and the advice from people who have done it is consistent about the shape of the approach, if not about whether it is worth the effort.
Top Echelon's version is to be an addition rather than a replacement: work alongside the existing panel on what it is not covering, rather than asking a buyer to displace a supplier they already have terms with. It also notes that a preferred supplier agreement "includes a time length and is reassessed once the time is up," which is the same fact the published contracts above put dates on.
The counter-position is worth reading too. RecruiterU argues against pursuing entry at all: "I am not going to get on a preferred supplier list so maybe, someday, hopefully, I can work with them." Its recommendation is to work smaller companies that do not run a PSL, and to reach the ones that do through an internal champion, described as being brought "through the moat, through the thick wall."
Both are agency-side sources with something to sell, and neither publishes a success rate. What they agree on is the timescale, and it is measured in quarters.
One thing the buyer side adds, from a procurement-side account: companies with a PSL still field calls from agencies outside it. So the sentence you got on the phone is sometimes a live contract and sometimes a way of ending a conversation, and the published register or tender notice will tell you which. For public-sector buyers, that document is online.
None of this makes a PSL company a bad prospect. It makes it a different kind of prospect, on a different clock, in a different pipeline from the one you work off live postings. The mistake is not calling them. The mistake is counting them in this quarter's numbers. With no fee history behind you the arithmetic is tighter still, and what a solo recruiter does about a locked requisition is a separate question from who signs the contract.
Frequently asked
- What does PSL stand for in recruitment?
- Preferred supplier list. It is a procurement arrangement in which a company appoints a named set of recruitment agencies for a fixed term and directs hiring managers to brief only those agencies during it. It is a contract with a start date, an end date and, at some buyers, a defined review window.
- How long does a PSL last?
- There is no standard term. Published UK examples run from two years, in the General Medical Council's case, to about four years for the national non-clinical staffing framework, with a three-year term plus a one-year extension option at one NHS trust. Some buyers also review their list annually, and one publishes that window as January to March.
- Can you work with a company that has a PSL?
- Sometimes, through a formal exception. One published PSL states that only appointed agencies may support recruitment "unless a specific, formally approved exception is in place," which means the exception exists and requires an internal approval rather than a persuasive phone call. Agencies also report that companies with a PSL still take calls from agencies outside it.
- What is the difference between RPO and a recruitment agency?
- Under recruitment process outsourcing, an employer transfers all or part of its recruitment process to an external provider, and that provider owns the design and management of the process and the results. A recruitment agency supplies candidates against a brief. The recruitment industry body's own definition draws this distinction explicitly, and it means that under an RPO contract, the party who can engage an agency is the provider rather than the employer.
- Does a live job posting mean a company is open to agencies?
- No. The posting says a role exists. Whether an outside agency can be engaged on it is decided by the company's procurement structure, which was set before the role was posted and does not change when a new requisition opens.