Services 1–4 are always counted from the sale date on the invoice. From the 5th service onward, each due date is calculated 90 days (editable above) after the customer's last completed service on record in the Service app — not from the sale date.
Reminder message template
{statusLine} automatically phrases the timing correctly — "is due on 12 Oct" for upcoming services, "is due today" for today, or "was due on 12 Oct and is now overdue by 9 days" once it's passed. {dueDate} on its own always gives the plain date if you want to phrase it yourself instead. Applies to both the WhatsApp and SMS reminder buttons on each vehicle card.