From the CMS HH Billing manual
Visits of any length are to be reported, rounding the time to the nearest15-minute increment.
See page 66 of the link below.
A visit of only 7 minutes or lesswould round down to 0 units, and that's not allowed for a chargeable visit. Avisit of 8 minutes would round up to 1 unit, so 8 minutes is the actual minimumchargeable visit.