Laws for Leaving a Child Home Alone. Only a couple of states have laws that specify the age when a child can be left home alone, including Maryland (age 8) and Illinois (age 14).However, most states have guidelines with the Department of Health and Human Services or other child protective agencies that test a child's ability to be left home alone. to 10 years-Should not be left alone for more than 1½ hours and only during daylight and early evening hours. 11 to 12 years-May be left alone for up to 3 hours but not late at night or in circumstances requiring inappropriate responsibility. 13 to 15 years-May be left unsupervised, but not overnight.