The federal government is looking to states to crack down on nursing homes that have inadequate staffing, particularly on weekends, by looking at the facilities’ payrolls.

The payroll data will be used to identify nursing homes that have a significant drop in staff on weekends or have several days in a quarter without a registered nurse on site, the federal Medicare agency said Nov. 30. Nursing homes must have a registered nurse on site every day for eight hours, the...