Drivers would receive a community sentence rather than a jail term if an accident was caused by a single, brief mistake and there were no aggravating factors, such as drink-driving.
The Sentencing Guidelines Council (SGC) says the rules would help judges to deliver the most appropriate punishment in "extremely sensitive" cases.
Careless driving is described as "a momentary negligent error of judgement", leading to standards that "fall below what would be expected of a competent and careful driver".
Examples include tuning a car radio, reading a map, lighting a cigarette, jumping a red light, driving too close to another car or overtaking on the inside.
"Very heavy sentences are appropriate where the standard of driving involves flagrant disregard of the safety of other road users," said the council's Deputy Chairman Sir Igor Judge.
"But sometimes death results from a relatively minor error of judgement, to which every, however experienced, motorist is liable from time to time.
"Cases like these present sentencing judges with very difficult decisions, because the gravest consequences have to be balanced against varying levels of culpability."
The guidelines suggest tougher sentences in serious cases, such as where more than one person is killed or where a driver has been drinking, going too fast or driving badly for a long period.
Those convicted of dangerous driving in the most serious cases should receive jail terms towards the 14-year maximum.
Reading or writing text messages for an extended period would be considered among the most serious offences.
The AA's head of road safety Andrew Howard said it was right for judges to have a range of sentencing options.
"It has to be recognised that there is strong public pressure for tougher sentences on drivers who kill, but it is for the courts to decide based on the weight of the evidence and circumstances," he said.
