What Is Bid-Rigging in UK Public Procurement?
An evergreen explainer — and a clear statement of the M&J investigation's status.
Last verified: 5 October 2026
IMPORTANT DISTINCTION
The penalties described on this website concern failures to comply with CMA investigative requirements during an inspection.
The separate CMA investigation into suspected bid-rigging remains ongoing.
The CMA has expressly stated that no assumption should currently be made that competition law has been infringed.
Bid-rigging is a form of anti-competitive conduct in which firms collude on the outcome of a tender process, rather than competing independently. It is prohibited under the Chapter I prohibition of the Competition Act 1998.
Common Methods
Cover bidding
One or more firms submit deliberately uncompetitive bids to allow another firm to win.
Bid suppression
A firm agrees not to bid, or to withdraw a bid, so another firm can win.
Bid rotation
Firms take turns being the winning bidder across a series of contracts.
Market allocation
Firms agree to divide customers, territories or contract types between them.
Information exchange
Firms share commercially sensitive information that reduces competitive independence.
These are generic, legitimate examples of bid-rigging methods. This page does not say M&J used any of these methods unless later officially established.
IMPORTANT DISTINCTION
The penalties described on this website concern failures to comply with CMA investigative requirements during an inspection.
The separate CMA investigation into suspected bid-rigging remains ongoing.
The CMA has expressly stated that no assumption should currently be made that competition law has been infringed.
The M&J Status
M&J is currently under investigation for suspected bid-rigging. No final infringement finding has yet been made.
CMA / GOV.UK — investigation into suspected anti-competitive conduct in roofing and construction [S001]