diff --git a/changelog.d/uc-capital-income-property-roles.fixed.md b/changelog.d/uc-capital-income-property-roles.fixed.md
new file mode 100644
index 0000000000..696d5a7757
--- /dev/null
+++ b/changelog.d/uc-capital-income-property-roles.fixed.md
@@ -0,0 +1 @@
+Gave the generated adults in the Universal Credit capital-income and State Pension property tests explicit claimant-or-partner roles, so an adult under 20 is no longer presumed to be the other adult's child.
diff --git a/policyengine_uk/tests/test_uc_income_from_capital_properties.py b/policyengine_uk/tests/test_uc_income_from_capital_properties.py
index 0bc207f5aa..6a2457cad9 100644
--- a/policyengine_uk/tests/test_uc_income_from_capital_properties.py
+++ b/policyengine_uk/tests/test_uc_income_from_capital_properties.py
@@ -115,7 +115,10 @@ def situation(units, year, income_scale=1.0, capital_bump=None):
         names = []
         for j, age in enumerate(unit["ages"]):
             name = f"p{i}_{j}"
-            person = {"age": {year: age}}
+            # The generated adults are the claimant and partner, as the FRS
+            # would record them; without this an adult under 20 who is 16 or
+            # more years younger is presumed to be the other's child.
+            person = {"age": {year: age}, "is_claimant_or_partner": {year: True}}
             if j == 0:
                 person["employment_income"] = {year: unit["earnings"]}
                 person["private_pension_income"] = {
@@ -128,7 +131,7 @@ def situation(units, year, income_scale=1.0, capital_bump=None):
             names.append(name)
         for k, age in enumerate(unit["children"]):
             name = f"c{i}_{k}"
-            people[name] = {"age": {year: age}}
+            people[name] = {"age": {year: age}, "is_claimant_or_partner": {year: False}}
             names.append(name)
         benunit = {"members": names}
         reported = unit["reported_capital"]
diff --git a/policyengine_uk/tests/test_uc_state_pension_properties.py b/policyengine_uk/tests/test_uc_state_pension_properties.py
index 70ee6af404..5e4115bcde 100644
--- a/policyengine_uk/tests/test_uc_state_pension_properties.py
+++ b/policyengine_uk/tests/test_uc_state_pension_properties.py
@@ -105,7 +105,14 @@ def situation(units, year, income_variable="state_pension", pension_bump=0.0):
         names = []
         for j, age in enumerate(unit["ages"]):
             name = f"p{i}_{j}"
-            person = {"age": {year: age}, "state_pension": {year: 0.0}}
+            # The generated adults are the claimant and partner (a mixed-age
+            # couple can include an 18- or 19-year-old partner), as the FRS
+            # would record them.
+            person = {
+                "age": {year: age},
+                "state_pension": {year: 0.0},
+                "is_claimant_or_partner": {year: True},
+            }
             if j == 0:
                 amount = unit["state_pension"] + pension_bump
                 person[income_variable] = {year: amount}
@@ -115,7 +122,7 @@ def situation(units, year, income_variable="state_pension", pension_bump=0.0):
             names.append(name)
         for k, age in enumerate(unit["children"]):
             name = f"c{i}_{k}"
-            people[name] = {"age": {year: age}}
+            people[name] = {"age": {year: age}, "is_claimant_or_partner": {year: False}}
             names.append(name)
         benunits[f"b{i}"] = {"members": names}
         households[f"h{i}"] = {