The IRS reported Wednesday that it has collected $1 billion in taxes and penalties owed by hundreds of wealthy households who accumulated past-due tax debts for years   IRS enforcement dwindled.

“The tax bill wasn’t even in dispute — the taxes were clearly owed by these people,” IRS Commissioner Danny Werfel said in a call with reporters. “But we didn’t have the people or the resources. … It takes time and staffing to work through these cases.”