A recent Senate report shows that Washington has a lot of work to do in cracking down on offshore tax havens. These schemes have allowed some wealthy Americans to evade up to $70 billion a year in taxes, and corporations are wrongly avoiding up to $30 billion in taxes.

According to the report adopted by a Senate subcommittee, individuals and companies hide assets using sham corporations and complex transactions.

Some individuals who used these schemes did not understand them and relied on professionals who told them the arrangements were legal.

The tax shelters were set up in locations with weak or nonexistent financial reporting laws, including the Cayman Islands, Belize, the British Virgin Islands or the Isle of Man.

Among the remedies recommended were more stringent reporting requirements and stiffer penalties for banks, law and accounting firms and investment advisers involved in the scams.

Congress should take steps to curb these improper tax shelters. They are unfair to average Americans who faithfully file their tax forms and pay through automatic withholding.