'cause extra costs' is a correct and usable phrase in written English.
You can use it when describing the result of a particular action. For example, "The renovation project caused extra costs that we had not foreseen."
Sedgemoor District Council has said its "primary concern" is that the restructure will not cause extra costs to its taxpayers.
Participation did not cause extra costs for businesses, and under the responsibility of the local authorities, the physical food inspections remained unchanged.
It should be kept in mind that all these handlings and treatments cause extra costs, and it is questionable whether these are cost-effective.
T-Mobile Germany now tries to charge €9.95 per month for a VoIP option because its "always on" nature causes "extra costs".
In the design of safety critical systems, engineers have to find trade-offs between different safety attributes, as well as between safety and costs, because in most cases the improvement of one safety attribute can't be achieved without causing extra costs or decreasing another safety attribute.
If business owners do care, then transparency schemes may work as an incentive that improves a business's hygiene without causing extra cost for the regulator.
Due to that the introduction of the decision protocol was not allowed to cause significant extra costs, data not regularly collected in the child health centre setting were disregarded.
This caused extra delays and costs for the study.
The risk for nosocomial infections (NI) in ICUs is five to 10 times higher than in other hospital care units, causing extra morbidity, mortality and costs.
This caused extra work to be done on the exterior to the tunnel, and costs had increased by several tens of millions of kroner.
