Two police forces already collaborating on major crimes such as murder and with a joint anti-corruption committee are considering a complete merger.
Bedfordshire and Hertfordshire police forces believe a merger, which could cost an initial £20m, could save money.
A study is under way to examine the benefits of the merger and a report is expected by the end of September.
Both forces have said they need to save money to keep the council tax precept as low as possible.
Chairman of Bedfordshire Police Authority, Peter Connif, said many operations were already shared but the full merger would not go through until they were sure there was a strong financial case.
Joint firearms unit
"The joint serious crime team saved resources because a lot of experienced officers could be put on to a murder case in a short time without abstracting them from front line duties," he said.
"We are now getting the figures ready on a full merger but this will not happen unless there are significant benefits and cost savings.
"We would also be looking for the Home Office to help with the set up funding of £20m and this will not be forthcoming if we do not have a very strong case."
Hertfordshire Police said they had developing a range of joint units.
A spokesperson said: "These include the Bedfordshire and Hertfordshire Major Crime Unit and the joint dog unit which have enabled us to deliver a more resilient and efficient policing service."
The two forces also have a joint firearms unit which became operational this month.