diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29bb..f80112b67 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,5 @@
+- bump: minor
+  changes:
+    changed:
+    - A variable must have a label.
+    - If a variable has formulas then it must not have adds/subtracts, and vice versa.
\ No newline at end of file
diff --git a/policyengine_core/variables/variable.py b/policyengine_core/variables/variable.py
index 4674d26c1..8fa44435e 100644
--- a/policyengine_core/variables/variable.py
+++ b/policyengine_core/variables/variable.py
@@ -187,6 +187,12 @@ def __init__(self, baseline_variable=None):
         self.label = self.set(
             attr, "label", allowed_type=str, setter=self.set_label
         )
+
+        if self.label is None:
+            raise ValueError(
+                'Variable "{name}" has no label'.format(name=self.name)
+            )
+
         self.end = self.set(attr, "end", allowed_type=str, setter=self.set_end)
         self.reference = self.set(attr, "reference", setter=self.set_reference)
         self.cerfa_field = self.set(
@@ -286,6 +292,15 @@ def __init__(self, baseline_variable=None):
                 )
             )
 
+        if len(self.formulas) != 0 and (
+            self.adds is not None or self.subtracts is not None
+        ):
+            raise ValueError(
+                'Variable "{name}" has a formula and an add or subtract'.format(
+                    name=self.name
+                )
+            )
+
         self.is_neutralized = False
 
     # ----- Setters used to build the variable ----- #
diff --git a/tests/core/parameters/operations/test_nesting.py b/tests/core/parameters/operations/test_nesting.py
index 3ba110d01..a4a808798 100644
--- a/tests/core/parameters/operations/test_nesting.py
+++ b/tests/core/parameters/operations/test_nesting.py
@@ -39,6 +39,7 @@ class country(Variable):
         definition_period = ETERNITY
         possible_values = Country
         default_value = Country.ENGLAND
+        label = "country"
 
     class Region(Enum):
         NORTH_EAST = "North East"
@@ -60,11 +61,13 @@ class region(Variable):
         definition_period = ETERNITY
         possible_values = Region
         default_value = Region.NORTH_EAST
+        label = "region"
 
     class family_size(Variable):
         value_type = int
         entity = Person
         definition_period = ETERNITY
+        label = "family size"
 
     from policyengine_core.parameters import homogenize_parameter_structures
     from policyengine_core.taxbenefitsystems import TaxBenefitSystem
diff --git a/tests/core/test_calculate_output.py b/tests/core/test_calculate_output.py
index b849a9d5f..7211afb58 100644
--- a/tests/core/test_calculate_output.py
+++ b/tests/core/test_calculate_output.py
@@ -10,6 +10,7 @@ class simple_variable(Variable):
     entity = entities.Person
     definition_period = periods.MONTH
     value_type = int
+    label = "simple variable"
 
 
 class variable_with_calculate_output_add(Variable):
@@ -17,6 +18,7 @@ class variable_with_calculate_output_add(Variable):
     definition_period = periods.MONTH
     value_type = int
     calculate_output = simulations.calculate_output_add
+    label = "variable with calculate_output_add"
 
 
 class variable_with_calculate_output_divide(Variable):
@@ -24,6 +26,7 @@ class variable_with_calculate_output_divide(Variable):
     definition_period = periods.YEAR
     value_type = int
     calculate_output = simulations.calculate_output_divide
+    label = "variable with calculate_output_divide"
 
 
 @pytest.fixture(scope="module", autouse=True)
diff --git a/tests/core/test_cycles.py b/tests/core/test_cycles.py
index e65e699df..cee41bbac 100644
--- a/tests/core/test_cycles.py
+++ b/tests/core/test_cycles.py
@@ -22,6 +22,7 @@ class variable1(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 1"
 
     def formula(person, period):
         return person("variable2", period)
@@ -31,6 +32,7 @@ class variable2(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 2"
 
     def formula(person, period):
         return person("variable1", period)
@@ -41,6 +43,7 @@ class variable3(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 3"
 
     def formula(person, period):
         return person("variable4", period.last_month)
@@ -50,6 +53,7 @@ class variable4(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 4"
 
     def formula(person, period):
         return person("variable3", period)
@@ -61,6 +65,7 @@ class variable5(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 5"
 
     def formula(person, period):
         variable6 = person("variable6", period.last_month)
@@ -71,6 +76,7 @@ class variable6(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 6"
 
     def formula(person, period):
         variable5 = person("variable5", period)
@@ -81,6 +87,7 @@ class variable7(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "variable 7"
 
     def formula(person, period):
         variable5 = person("variable5", period)
@@ -92,6 +99,7 @@ class cotisation(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "cotisation"
 
     def formula(person, period):
         if period.start.month == 12:
diff --git a/tests/core/test_formulas.py b/tests/core/test_formulas.py
index 08f1c1603..3504283a3 100644
--- a/tests/core/test_formulas.py
+++ b/tests/core/test_formulas.py
@@ -11,6 +11,7 @@ class choice(Variable):
     value_type = int
     entity = entities.Person
     definition_period = periods.MONTH
+    label = "choice"
 
 
 class uses_multiplication(Variable):
@@ -18,6 +19,7 @@ class uses_multiplication(Variable):
     entity = entities.Person
     label = "Variable with formula that uses multiplication"
     definition_period = periods.MONTH
+    label = "uses multiplication"
 
     def formula(person, period):
         choice = person("choice", period)
@@ -30,6 +32,7 @@ class returns_scalar(Variable):
     entity = entities.Person
     label = "Variable with formula that returns a scalar value"
     definition_period = periods.MONTH
+    label = "returns scalar"
 
     def formula(person, period):
         return 666
@@ -40,6 +43,7 @@ class uses_switch(Variable):
     entity = entities.Person
     label = "Variable with formula that uses switch"
     definition_period = periods.MONTH
+    label = "uses switch"
 
     def formula(person, period):
         choice = person("choice", period)
@@ -154,11 +158,13 @@ class household_level_variable(Variable):
         value_type = int
         entity = household_entity
         definition_period = ETERNITY
+        label = "household level variable"
 
     class projected_family_level_variable(Variable):
         value_type = int
         entity = family_entity
         definition_period = ETERNITY
+        label = "projected family level variable"
 
         def formula(family, period):
             return family.household("household_level_variable", period)
diff --git a/tests/core/test_projectors.py b/tests/core/test_projectors.py
index 765a608b7..a2e3444af 100644
--- a/tests/core/test_projectors.py
+++ b/tests/core/test_projectors.py
@@ -137,6 +137,7 @@ class household_enum_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = household
         definition_period = ETERNITY
+        label = "household enum variable"
 
     class projected_enum_variable(Variable):
         value_type = Enum
@@ -144,6 +145,7 @@ class projected_enum_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = person
         definition_period = ETERNITY
+        label = "projected enum variable"
 
         def formula(person, period):
             return person.household("household_enum_variable", period)
@@ -210,6 +212,7 @@ class household_projected_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = household
         definition_period = ETERNITY
+        label = "household projected variable"
 
         def formula(household, period):
             return household.value_from_first_person(
@@ -222,6 +225,7 @@ class person_enum_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = person
         definition_period = ETERNITY
+        label = "person enum variable"
 
     system.add_variables(household_projected_variable, person_enum_variable)
 
@@ -303,6 +307,7 @@ class household_level_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = household_entity
         definition_period = ETERNITY
+        label = "household level variable"
 
     class projected_family_level_variable(Variable):
         value_type = Enum
@@ -310,6 +315,7 @@ class projected_family_level_variable(Variable):
         default_value = enum.FIRST_OPTION
         entity = family_entity
         definition_period = ETERNITY
+        label = "projected family level variable"
 
         def formula(family, period):
             return family.household("household_level_variable", period)
@@ -318,6 +324,7 @@ class decoded_projected_family_level_variable(Variable):
         value_type = str
         entity = family_entity
         definition_period = ETERNITY
+        label = "decoded projected family level variable"
 
         def formula(family, period):
             return family.household(
diff --git a/tests/core/test_simulation_builder.py b/tests/core/test_simulation_builder.py
index 4ed4fbe08..d9c064be7 100644
--- a/tests/core/test_simulation_builder.py
+++ b/tests/core/test_simulation_builder.py
@@ -19,6 +19,7 @@ class intvar(Variable):
         definition_period = periods.ETERNITY
         value_type = int
         entity = persons
+        label = "int variable"
 
         def __init__(self):
             super().__init__()
@@ -32,6 +33,7 @@ class datevar(Variable):
         definition_period = periods.ETERNITY
         value_type = datetime.date
         entity = persons
+        label = "date variable"
 
         def __init__(self):
             super().__init__()
@@ -50,6 +52,7 @@ class TestEnum(Variable):
         set_input = None
         possible_values = Enum("foo", "bar")
         name = "enum"
+        label = "enum variable"
 
         def __init__(self):
             pass
diff --git a/tests/core/variables/test_annualize.py b/tests/core/variables/test_annualize.py
index a36b8d05d..61f8168b8 100644
--- a/tests/core/variables/test_annualize.py
+++ b/tests/core/variables/test_annualize.py
@@ -15,6 +15,7 @@ class monthly_variable(Variable):
         value_type = int
         entity = Person
         definition_period = MONTH
+        label = "monthly variable"
 
         def formula(person, period, parameters):
             variable.calculation_count += 1
diff --git a/tests/core/variables/test_variables.py b/tests/core/variables/test_variables.py
index aad2fa1db..12e5e8acb 100644
--- a/tests/core/variables/test_variables.py
+++ b/tests/core/variables/test_variables.py
@@ -612,3 +612,103 @@ class variable_with_strange_attr(Variable):
 
     with raises(ValueError):
         tax_benefit_system.add_variable(variable_with_strange_attr)
+
+
+class variable__one_formula_one_add(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+    label = "Variable with one formula and one add."
+    adds = ["pass"]
+
+    def formula():
+        pass
+
+
+def test_one_formula_one_add():
+    check_error_at_add_variable(
+        tax_benefit_system,
+        variable__one_formula_one_add,
+        'Variable "{name}" has a formula and an add or subtract'.format(
+            name="variable__one_formula_one_add"
+        ),
+    )
+
+
+class variable__one_formula_one_subtract(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+    label = "Variable with one formula and one subtract."
+    adds = ["pass"]
+
+    def formula():
+        pass
+
+
+def test_one_formula_one_subtract():
+    check_error_at_add_variable(
+        tax_benefit_system,
+        variable__one_formula_one_subtract,
+        'Variable "{name}" has a formula and an add or subtract'.format(
+            name="variable__one_formula_one_subtract"
+        ),
+    )
+
+
+class variable__one_formula(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+    label = "Variable with one formula."
+
+    def formula():
+        pass
+
+
+def test_one_formula():
+    tax_benefit_system.add_variable(variable__one_formula)
+    variable = tax_benefit_system.variables["variable__one_formula"]
+    assert len(variable.formulas)
+
+
+class variable__one_add(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+    label = "Variable with one add."
+    adds = ["pass"]
+
+
+def test_one_add():
+    tax_benefit_system.add_variable(variable__one_add)
+    variable = tax_benefit_system.variables["variable__one_add"]
+    assert len(variable.adds)
+
+
+class variable__one_subtract(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+    label = "Variable with one subtract."
+    subtracts = ["pass"]
+
+
+def test_one_subtract():
+    tax_benefit_system.add_variable(variable__one_subtract)
+    variable = tax_benefit_system.variables["variable__one_subtract"]
+    assert len(variable.subtracts)
+
+
+class variable__no_label(Variable):
+    value_type = int
+    entity = Person
+    definition_period = MONTH
+
+
+def test_no_label():
+    check_error_at_add_variable(
+        tax_benefit_system,
+        variable__no_label,
+        'Variable "{name}" has no label'.format(name="variable__no_label"),
+    )
diff --git a/tests/fixtures/variables.py b/tests/fixtures/variables.py
index 79d28d146..600107515 100644
--- a/tests/fixtures/variables.py
+++ b/tests/fixtures/variables.py
@@ -6,6 +6,7 @@
 class TestVariable(Variable):
     definition_period = periods.ETERNITY
     value_type = float
+    label = "test variable"
 
     def __init__(self, entity):
         self.__class__.entity = entity