---
title: "Why didn't the sibling discount apply?"
description: "The rule picks the younger children by date of birth at billing time. Separate families, a missing DOB or plan, or a date window are the usual causes."
type: troubleshoot
updated: 2026-10-09
canonical_url: https://help.nestlicare.com/owners/faq/why-didnt-the-sibling-discount-apply
roles: ["super_admin", "center_admin"]
platforms: [web]
---
The sibling discount is worked out **at billing time, by the children's ages**. NestliCare orders a family's children by date of birth and applies the rule to the younger ones. You never tag a child as "the second child".

So when it does not apply, check:

1. **Are the children in the same family?** Siblings split across two family cards look like two only children.
2. **Do both children have a date of birth?** A child with no DOB is sorted last, as if youngest, so the discount may land on them instead of the actual younger child. Fill it in on the child's profile.
3. **Is every sibling on a billing plan?** Only children billed on this invoice through a plan count. A sibling with no plan doesn't, so the other child is billed as an only child.
4. **Does the discount's date window overlap the invoice's billing period?** A rule with an end date stops firing once no part of a period overlaps it.
5. **Was the discount active before the invoice was generated?** Discounts apply at generation time. A rule you added today reaches the next invoice, never existing ones.

Fix the cause, then have a super admin void the wrong invoice and create a corrected one; existing invoices keep their original figures.

Related: [Subsidies and discounts](/owners/billing/subsidies-and-discounts), [Credits and referral bonuses](/owners/billing/family-credits).