A survey by the UK and Ireland Institute of Travel Management (ITM) has found that a large minority of travellers are going off policy and off track.
The survey of 80 buyers with a combined travel spend of £800m, found that one in ten travellers booked trips outside mandated booking channels while a further 10% booked trips on the right channels but not with preferred suppliers.
About 10% of travellers who booked of policy also disappeared off the "company radar" while away.
Paul Tilstone, executive director of ITM, commenting on the survey, said that between 15%-30% of travellers were "simply doing their own thing."
He said the level of non-compliance seemed to be affecting larger companies with a spend of £20m far more than smaller ones.
"The key drivers behind this are internet access and choice, increase traveller awareness of alternative booking methods and the appeal of airline and hotel loyalty schemes," Mr Tilstone said.
He said 40% of the buyers questioned now had access to pre-trip information to weed out the rogue bookers.
This included access to real-time information rather than waiting for agents to pass on the information.
He said that those who "disappeared" while away were putting themselves at risk.
"Independent travellers effectively disappear from the corporate radar have no access to the 24 hour global emergency and support services provided by the travel management companies and would become extremely difficult to locate in an emergency or crisis situation," Mr Tilstone said.
"The employer suffers because the trip booked outside company policy does not contribute towards any volume deals negotiated with travel suppliers, is not being captured in any management information data but the traveller's expense claim still needs to be processed.
"So the cost of a trip ends up being much higher. Few travellers realise this."