Police are failing to record violent and sexual offences as they admit crime rates are going to rise.
Inspectors are expected to criticise Norfolk police for failing to record crimes accurately when they report later this year.
The force has denied they are "trying to suppress crime" and said they have funnelled their resources into front line police officers.
Assistant chief constable Paul Sanford said: "Our priority has been to maximise the number of officers and if we are guilty of anything it is neglecting the administrative side of policing."
He said the force will immediately invest in an audit team to give them a "better picture of crime in the county".
Police and crime commissioner Lorne Green said police have a "duty" to Norfolk to record all crime, and this would be a "wake up call" for the force.
ACC Sanford said the force does not have a central crime recording team, as other forces do.
That team would assess all crimes and make sure everything is recorded accurately.
"Up until now we have resisted that because it would cost hundreds of thousands of pounds," he said.
"We have wanted to prioritise getting the maximum number of officers to the scene rather than managing the administrative process."
Instead Norfolk Police has hoped training officers on crime recording practices would suffice, with a small audit team to "sweep" a selection of reports for accuracy.
"The consequence of that is we are missing a proportion of the crimes that should be recorded," said ACC Sanford.
He said one of the reasons crime recording is lacking is the difference between reports made to the control room and what is said to an officer at the scene.
"These are secondary crimes," he said. "We go to an address and investigate the main thing in front of us, but there is often a second, more technical offence we are missing.
"Her Majesty's Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS) will inevitably report on the fact we need to improve crime recording and the accuracy of it.
"The only way now, in a sense reluctantly, is to put resources into the back office.
"The consequence of that is there will be an increase in [recorded] crime. We need to tighten up our crime recording so we can give a better picture of crime across the county, but that comes at a cost."
With more crimes going onto the books, ACC Sanford said the proportion of crimes solved will "inevitably" go down.
"Some of that crime on paper looks horrendous," he said. "There will be some sexual offences we miss within that.
"We provide support to the victim and best evidence to court but there might be a time when HMICFRS say to us you are missing rapes and sexual offences.
"We are going to have to put in more funding when we have tried to resist that for as long as possible.
"The areas we are most likely to see a rise in crime and reduction in solve rate is violent crime. When it is reported there is an increased chance the victim is vulnerable, distressed or upset, so we get variance in the detail that is reported. Often the violence is the symptom of a bigger issue going on in that person's life, like coercive control.
"We have absolute confidence this is not about the service we are giving to victims or that we have tried to suppress crime.
"This is about our very busy service not having the time to dot all the Is or cross all the Ts, and wanting to put our resources on the streets. It is about where we believe the public want us to spend their money."
Chief constable Simon Bailey added one issue with crime recording is the "young workforce" after a recent recruitment drive.
"The organisation is a young one, and one that is learning," he said.
"There have been some pinch points with the rollout of the policing model and there are some areas we are going to have to improve.
"We have done our best to protect the front line but it has come at a cost in terms of crime recording. That was a conscious decision based on the fact we have done everything we can to raise awareness and understanding for officers and supervisors to get crime recording right.
"We have had the challenge of rolling out a new policing model and I think we have had the best summer we have had for many years. Despite our best efforts, recording is not as good as it should be."
Police and crime commissioner Lorne Green said: "They must give attention to the most serious alleged crimes they confront. There may be related crimes surrounding the principal issue that perhaps are getting overlooked on occasion.
"This is a wake up call for them. It is entirely right and appropriate that all crimes, no matter how seemingly slight, are recorded. That is a duty owed to the Norfolk community."
HMICFRS are expected to report back on crime recording practices in December.
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