Tens of thousands of criminals, including sex offenders, shoplifters, drug dealers and violent thugs, will avoid jail altogether under government reforms to sentencing laws being put forward to MPs next month.

The Sentencing Bill will encourage judges to presume against prison time for sentences shorter than 12 months in an attempt to counteract Britain’s prison overcrowding crisis.

Shabana Mahmood, the justice secretary, announced plans in May to scrap prison sentences of less than 12 months except where “exceptional circumstances” meant custody was necessary.

A presumption against short sentences was a principal recommendation of The Times Crime and Justice Commission, which made suggestions to the government on how to fix problems in the criminal justice system in England and Wales.

Under the proposed changes, offenders will mostly be given community sentences, apart from in exceptional circumstances where judges could still impose prison time.