diff --git a/models/staging/xero/schema.yml b/models/staging/xero/schema.yml
index 6ba2c34..c07e69a 100644
--- a/models/staging/xero/schema.yml
+++ b/models/staging/xero/schema.yml
@@ -320,6 +320,11 @@ models:
       - name: invoice_currency_iso_4217
         data_type: character varying
         description: The ISO 4217 code for the currency which this invoice uses as unit of account.
+        tests:
+          - not_null
+          - length_between:
+              min_length: 3
+              max_length: 3
 
       - name: exchange_rate_to_gbp
         data_type: numeric
@@ -331,6 +336,9 @@ models:
 
           For example, if the invoice is 135 ZAR, and this rate is 0.0167, the invoice value in GBP is 2.25 
           (135ZAR * 0.0167GBP/ZAR = 2.25GBP).
+        tests:
+          - not_null
+          - not_negative
 
       - name: is_discounted
         data_type: boolean
@@ -390,6 +398,12 @@ models:
           Indicates whether the amounts included in line items are tax 
           inclusive (Inclusive), tax exclusive (Exclusive) or simply,
           there are no taxes on the invoice (NoTax).
+        tests:
+          - accepted_values:
+              values:
+                - Inclusive
+                - Exclusive
+                - NoTax
 
       - name: payment_planned_date_utc
         data_type: timestamp with time zone