> For the complete documentation index, see [llms.txt](https://help.tahua.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.tahua.io/knowledge-base/administrator-help-guides/payments/payments-faqs.md).

# Payments FAQs

**What's the difference between a Milestone Payment, an Application Payment, and a Contact Payment?**

A Milestone Payment is tied to a specific approved Milestone, with its amount coming from that Milestone. An Application Payment is a lump-sum payment tied directly to a Funding Application rather than any one Milestone. A Contact Payment is made to a specific contact/Applicant outside the context of a particular Application or Milestone. See [Payments Overview](/knowledge-base/administrator-help-guides/payments/payments-overview.md) for the full breakdown of when to use each.

**How is GST calculated on a payment?**

This depends on the payment type. For a Milestone Payment, GST is inherited directly from the Milestone itself. For an Application or Contact Payment (which aren't tied to a Milestone), GST is instead calculated from the recipient's own GST registration status at the point the payment syncs to Xero or QuickBooks.

**Can I edit a payment after it's been approved or paid?**

The Amount, Paid Date, and GST Amount remain editable regardless of the payment's current state. Take care making changes to a payment that's already synced to Xero or QuickBooks though — editing it in Tahua afterwards won't automatically update the corresponding bill on the accounting side, so you may need to adjust it there too.

**What happens if a payment fails to sync to Xero or QuickBooks?**

The payment is flagged for manual sync only, and the Admin assigned to it receives an error email explaining what went wrong (a common cause is a locked period in your accounting system). A **Resync** button will appear on the payment so you can retry once the issue is resolved. If a payment has already synced successfully, you'll see a **View in Xero** link instead, taking you straight to the bill.