diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29bb..8515e2ff7 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,7 @@
+- bump: minor
+  changes:
+    added:
+    - Firm dataset support with 3 new entities (firm, sector, business_group)
+    - 16 firm variables for business microdata analysis
+    - UKFirmSingleYearDataset class for firm data handling
+    - FIRM_2023_24 dataset constant for firm_2023_24.h5 integration
\ No newline at end of file
diff --git a/policyengine_uk/__init__.py b/policyengine_uk/__init__.py
index 727ce05c5..2b1d6fd51 100644
--- a/policyengine_uk/__init__.py
+++ b/policyengine_uk/__init__.py
@@ -6,6 +6,7 @@
     CountryTaxBenefitSystem,
     Microsimulation,
     Simulation,
+    FirmSimulation,
     COUNTRY_DIR,
     parameters,
     variables,
diff --git a/policyengine_uk/data/__init__.py b/policyengine_uk/data/__init__.py
index 905fb1306..9ee80a30a 100644
--- a/policyengine_uk/data/__init__.py
+++ b/policyengine_uk/data/__init__.py
@@ -2,3 +2,6 @@
     UKMultiYearDataset,
     UKSingleYearDataset,
 )
+from policyengine_uk.data.firm_dataset_schema import (
+    UKFirmSingleYearDataset,
+)
diff --git a/policyengine_uk/data/firm_dataset_schema.py b/policyengine_uk/data/firm_dataset_schema.py
new file mode 100644
index 000000000..e3684707f
--- /dev/null
+++ b/policyengine_uk/data/firm_dataset_schema.py
@@ -0,0 +1,138 @@
+import pandas as pd
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from policyengine_uk import Microsimulation
+
+from pathlib import Path
+import h5py
+
+
+class UKFirmSingleYearDataset:
+    firm: pd.DataFrame
+    sector: pd.DataFrame
+    business_group: pd.DataFrame
+
+    @staticmethod
+    def validate_file_path(file_path: str, raise_exception: bool = True):
+        if not file_path.endswith(".h5"):
+            if raise_exception:
+                raise ValueError(
+                    "File path must end with '.h5' for UKFirmDataset."
+                )
+            return False
+        if not Path(file_path).exists():
+            if raise_exception:
+                raise FileNotFoundError(f"File not found: {file_path}")
+            return False
+
+        # Check if the file contains time_period, firm, sector, and business_group datasets
+        with h5py.File(file_path, "r") as f:
+            required_datasets = [
+                "time_period",
+                "firm",
+                "sector",
+                "business_group",
+            ]
+            for dataset in required_datasets:
+                if dataset not in f:
+                    if raise_exception:
+                        raise ValueError(
+                            f"Dataset '{dataset}' not found in the file: {file_path}"
+                        )
+                    else:
+                        return False
+
+        return True
+
+    def __init__(
+        self,
+        file_path: str = None,
+        firm: pd.DataFrame = None,
+        sector: pd.DataFrame = None,
+        business_group: pd.DataFrame = None,
+        fiscal_year: int = 2025,
+    ):
+        file_path = str(file_path) if file_path else None
+        if file_path is not None:
+            self.validate_file_path(file_path)
+            with pd.HDFStore(file_path) as f:
+                self.firm = f["firm"]
+                self.sector = f["sector"]
+                self.business_group = f["business_group"]
+                self.time_period = str(f["time_period"].iloc[0])
+        else:
+            if firm is None or sector is None or business_group is None:
+                raise ValueError(
+                    "Must provide either a file path or all three DataFrames (firm, sector, business_group)."
+                )
+            self.firm = firm
+            self.sector = sector
+            self.business_group = business_group
+            self.time_period = str(fiscal_year)
+
+        self.data_format = "arrays"
+        self.tables = (self.firm, self.sector, self.business_group)
+        self.table_names = ("firm", "sector", "business_group")
+
+    def save(self, file_path: str):
+        with pd.HDFStore(file_path) as f:
+            f.put("firm", self.firm, format="table", data_columns=True)
+            f.put("sector", self.sector, format="table", data_columns=True)
+            f.put(
+                "business_group",
+                self.business_group,
+                format="table",
+                data_columns=True,
+            )
+            f.put("time_period", pd.Series([self.time_period]), format="table")
+
+    def load(self):
+        data = {}
+        for df in (self.firm, self.sector, self.business_group):
+            for col in df.columns:
+                data[col] = df[col].values
+
+        return data
+
+    def copy(self):
+        return UKFirmSingleYearDataset(
+            firm=self.firm.copy(),
+            sector=self.sector.copy(),
+            business_group=self.business_group.copy(),
+            fiscal_year=self.time_period,
+        )
+
+    def validate(self):
+        # Check for NaNs in the tables
+        for df in self.tables:
+            for col in df.columns:
+                if df[col].isna().any():
+                    raise ValueError(f"Column '{col}' contains NaN values.")
+
+    @staticmethod
+    def from_simulation(
+        simulation: "Microsimulation", fiscal_year: int = 2025
+    ):
+        entity_dfs = {}
+
+        for entity in ["firm", "sector", "business_group"]:
+            input_variables = [
+                variable
+                for variable in simulation.input_variables
+                if simulation.tax_benefit_system.variables[variable].entity.key
+                == entity
+            ]
+            if len(input_variables) == 0:
+                entity_dfs[entity] = pd.DataFrame()
+            else:
+                entity_dfs[entity] = simulation.calculate_dataframe(
+                    input_variables, period=fiscal_year
+                )
+
+        return UKFirmSingleYearDataset(
+            firm=entity_dfs["firm"],
+            sector=entity_dfs["sector"],
+            business_group=entity_dfs["business_group"],
+            fiscal_year=fiscal_year,
+        )
diff --git a/policyengine_uk/entities.py b/policyengine_uk/entities.py
index d83ee53b2..3130fa68e 100644
--- a/policyengine_uk/entities.py
+++ b/policyengine_uk/entities.py
@@ -43,4 +43,42 @@
     is_person=True,
 )
 
-entities = [Household, BenUnit, Person]
+Firm = build_entity(
+    key="firm",
+    plural="firms",
+    label="Firm",
+    doc="A business entity with employees and operations.",
+    is_person=True,
+)
+
+Sector = build_entity(
+    key="sector",
+    plural="sectors",
+    label="Sector",
+    doc="An economic sector containing multiple firms.",
+    roles=[
+        {
+            "key": "member",
+            "plural": "members",
+            "label": "Member",
+            "doc": "A sector in the business classification.",
+        }
+    ],
+)
+
+BusinessGroup = build_entity(
+    key="business_group",
+    plural="business_groups",
+    label="Business Group",
+    doc="A business group containing multiple firms.",
+    roles=[
+        {
+            "key": "member",
+            "plural": "members",
+            "label": "Member",
+            "doc": "A business group in the firm dataset.",
+        }
+    ],
+)
+
+entities = [Household, BenUnit, Person, Firm, Sector, BusinessGroup]
diff --git a/policyengine_uk/firm_simulation.py b/policyengine_uk/firm_simulation.py
new file mode 100644
index 000000000..b30a6ba83
--- /dev/null
+++ b/policyengine_uk/firm_simulation.py
@@ -0,0 +1,135 @@
+"""Firm-specific simulation class for business microdata analysis."""
+
+from typing import Dict, Optional, Union, List
+import numpy as np
+import pandas as pd
+
+from policyengine_core.simulations.simulation import Simulation
+from policyengine_uk.data.firm_dataset_schema import UKFirmSingleYearDataset
+from policyengine_uk.firm_tax_benefit_system import FirmTaxBenefitSystem
+
+
+class FirmSimulation(Simulation):
+    """Firm-specific simulation class for business microdata.
+
+    This simulation handles firm, sector, and business_group entities
+    for business-level policy analysis.
+    """
+
+    default_input_period: int = 2025
+    default_calculation_period: int = 2025
+
+    def __init__(
+        self,
+        dataset: Optional[Union[UKFirmSingleYearDataset, str]] = None,
+        reform: Optional[Dict] = None,
+        trace: bool = False,
+    ):
+        """Initialize a firm simulation.
+
+        Args:
+            dataset: Firm dataset or path to firm dataset
+            reform: Optional reform to apply
+            trace: Whether to enable tracing
+        """
+        # Initialize firm tax benefit system
+        tax_benefit_system = FirmTaxBenefitSystem()
+
+        if reform is not None:
+            # Apply reform to the tax benefit system if needed
+            pass
+
+        # Build populations from dataset
+        if isinstance(dataset, str):
+            dataset = UKFirmSingleYearDataset(file_path=dataset)
+        elif dataset is None:
+            raise ValueError("FirmSimulation requires a firm dataset")
+        elif not isinstance(dataset, UKFirmSingleYearDataset):
+            raise ValueError(f"Unsupported dataset type: {dataset.__class__}")
+
+        # Create populations using the dataset
+        from policyengine_core.simulations.simulation_builder import (
+            SimulationBuilder,
+        )
+
+        builder = SimulationBuilder()
+        builder.populations = tax_benefit_system.instantiate_entities()
+
+        # Declare entities
+        builder.declare_person_entity("firm", dataset.firm.firm_id.values)
+        builder.declare_entity("sector", dataset.sector.sector_id.values)
+        builder.declare_entity(
+            "business_group", dataset.business_group.business_group_id.values
+        )
+
+        # Link firms to sectors and business groups
+        builder.join_with_persons(
+            builder.populations["sector"],
+            dataset.firm.firm_sector_id.values,
+            np.array(["member"] * len(dataset.firm)),
+        )
+        builder.join_with_persons(
+            builder.populations["business_group"],
+            dataset.firm.firm_business_group_id.values,
+            np.array(["member"] * len(dataset.firm)),
+        )
+
+        # Initialize the parent Simulation with populations
+        super().__init__(
+            tax_benefit_system=tax_benefit_system,
+            populations=builder.populations,
+        )
+
+        # Set up tracing if requested
+        if trace:
+            self.trace = True
+
+        # Load variable values from dataset
+        for table in dataset.tables:
+            for variable in table.columns:
+                if variable not in self.tax_benefit_system.variables:
+                    continue
+                self.set_input(
+                    variable, dataset.time_period, table[variable].values
+                )
+
+        self.dataset = dataset
+        self.input_variables = self.get_known_variables()
+
+    def get_known_variables(self) -> List[str]:
+        """Get list of variables with known values.
+
+        Returns:
+            List of variable names that have values set
+        """
+        known = []
+        for variable in self.tax_benefit_system.variables:
+            try:
+                if len(self.get_holder(variable).get_known_periods()) > 0:
+                    known.append(variable)
+            except:
+                pass
+        return known
+
+    def calculate_dataframe(
+        self,
+        variable_names: List[str],
+        period: Optional[int] = None,
+    ) -> pd.DataFrame:
+        """Calculate multiple variables and return as DataFrame.
+
+        Args:
+            variable_names: List of variables to calculate
+            period: Time period for calculation
+
+        Returns:
+            DataFrame with calculated values
+        """
+        if period is None:
+            period = self.default_calculation_period
+
+        data = {}
+        for variable in variable_names:
+            data[variable] = self.calculate(variable, period)
+
+        return pd.DataFrame(data)
diff --git a/policyengine_uk/firm_tax_benefit_system.py b/policyengine_uk/firm_tax_benefit_system.py
new file mode 100644
index 000000000..2dc3024d7
--- /dev/null
+++ b/policyengine_uk/firm_tax_benefit_system.py
@@ -0,0 +1,60 @@
+"""Firm-specific tax benefit system for business microdata."""
+
+import copy
+from pathlib import Path
+from typing import Any, Dict
+
+from policyengine_core.taxbenefitsystems import TaxBenefitSystem
+from policyengine_uk.entities import Firm, Sector, BusinessGroup
+from policyengine_uk.utils.parameters import backdate_parameters
+
+# Module constants
+COUNTRY_DIR = Path(__file__).parent
+
+
+class FirmTaxBenefitSystem(TaxBenefitSystem):
+    """Firm-specific tax and benefit system for business microdata.
+
+    This system handles firm, sector, and business_group entities
+    for business-level analysis.
+    """
+
+    def __init__(self):
+        """Initialize the firm tax-benefit system with business entities."""
+        self._parameters_at_instant_cache: Dict[str, Any] = {}
+        self.variables = {}
+
+        # Create copies of entity classes to avoid modifying originals
+        firm, sector, business_group = (
+            copy.copy(Firm),
+            copy.copy(Sector),
+            copy.copy(BusinessGroup),
+        )
+
+        # Set up entities
+        self.entities = [firm, sector, business_group]
+        self.person_entity = (
+            firm  # Firm is the "person" entity for this system
+        )
+        self.group_entities = [sector, business_group]
+        self.group_entity_keys = [entity.key for entity in self.group_entities]
+
+        # Link entities to this tax-benefit system
+        for entity in self.entities:
+            entity.set_tax_benefit_system(self)
+
+        self.variable_module_metadata = {}
+
+        # Add firm variables from separate directory
+        variables_firm_directory = COUNTRY_DIR / "variables_firm"
+        self.add_variables_from_directory(variables_firm_directory)
+
+        # Add parameters (if needed for firm calculations)
+        parameters_directory = COUNTRY_DIR / "parameters"
+        if parameters_directory.exists():
+            self.load_parameters(str(parameters_directory))
+            backdate_parameters(self.parameters)
+
+    def reset_parameter_caches(self):
+        """Reset parameter caches (compatibility method)."""
+        self._parameters_at_instant_cache = {}
diff --git a/policyengine_uk/parameters/gov/hmrc/vat/deregistration_threshold.yaml b/policyengine_uk/parameters/gov/hmrc/vat/deregistration_threshold.yaml
new file mode 100644
index 000000000..6c09fa672
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/vat/deregistration_threshold.yaml
@@ -0,0 +1,9 @@
+description: The United Kingdom requires firms to remain registered for Value Added Tax if their taxable turnover exceeds this amount.
+values:
+  2017-04-01: 83_000
+  2024-04-01: 88_000
+metadata:
+  unit: currency-GBP
+  reference:
+    - title: HMRC VAT registration thresholds
+      href: https://www.gov.uk/vat-registration-thresholds
\ No newline at end of file
diff --git a/policyengine_uk/parameters/gov/hmrc/vat/registration_threshold.yaml b/policyengine_uk/parameters/gov/hmrc/vat/registration_threshold.yaml
new file mode 100644
index 000000000..49aab5cc9
--- /dev/null
+++ b/policyengine_uk/parameters/gov/hmrc/vat/registration_threshold.yaml
@@ -0,0 +1,9 @@
+description: The United Kingdom requires firms to register for Value Added Tax when their taxable turnover exceeds this amount.
+values:
+  2017-04-01: 85_000
+  2024-04-01: 90_000
+metadata:
+  unit: currency-GBP
+  reference:
+    - title: HMRC VAT registration thresholds
+      href: https://www.gov.uk/vat-registration-thresholds
\ No newline at end of file
diff --git a/policyengine_uk/simulation.py b/policyengine_uk/simulation.py
index e2537d54b..d1aac5316 100644
--- a/policyengine_uk/simulation.py
+++ b/policyengine_uk/simulation.py
@@ -108,7 +108,9 @@ def __init__(
 
         # Universal Credit reform (July 2025). Needs closer integration in the baseline,
         # but adding here for ease of toggling on/off via the 'active' parameter.
-        from policyengine_uk.scenarios import universal_credit_july_2025_reform
+        from policyengine_uk.scenarios import (
+            universal_credit_july_2025_reform,
+        )
 
         universal_credit_july_2025_reform.simulation_modifier(self)
 
diff --git a/policyengine_uk/system.py b/policyengine_uk/system.py
index 5d926165a..e43123f0b 100644
--- a/policyengine_uk/system.py
+++ b/policyengine_uk/system.py
@@ -1,3 +1,4 @@
 from .tax_benefit_system import *
 from .simulation import *
 from .microsimulation import *
+from .firm_simulation import FirmSimulation
diff --git a/policyengine_uk/tax_benefit_system.py b/policyengine_uk/tax_benefit_system.py
index e76cddbd9..02b8da8f3 100644
--- a/policyengine_uk/tax_benefit_system.py
+++ b/policyengine_uk/tax_benefit_system.py
@@ -14,7 +14,14 @@
 from policyengine_core.variables import Variable
 
 # PolicyEngine UK imports
-from policyengine_uk.entities import BenUnit, Household, Person
+from policyengine_uk.entities import (
+    BenUnit,
+    Household,
+    Person,
+    Firm,
+    Sector,
+    BusinessGroup,
+)
 from policyengine_uk.parameters.gov.contrib.create_private_pension_uprating import (
     add_private_pension_uprating_factor,
 )
@@ -38,6 +45,7 @@
 # Module constants
 COUNTRY_DIR = Path(__file__).parent
 ENHANCED_FRS = "hf://policyengine/policyengine-uk-data/enhanced_frs_2023_24.h5"
+FIRM_2023_24 = "hf://policyengine/policyengine-uk-data/firm_2023_24.h5"
 
 
 class CountryTaxBenefitSystem(TaxBenefitSystem):
@@ -115,7 +123,11 @@ def __init__(self):
         )
 
         # Set up entities
-        self.entities = [person, benunit, household]
+        self.entities = [
+            person,
+            benunit,
+            household,
+        ]
         self.person_entity = person
         self.group_entities = [benunit, household]
         self.group_entity_keys = [entity.key for entity in self.group_entities]
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_net_vat_liability.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_net_vat_liability.py
new file mode 100644
index 000000000..39a0a15d0
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_net_vat_liability.py
@@ -0,0 +1,17 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_net_vat_liability(Variable):
+    value_type = float
+    entity = Firm
+    label = "Net VAT liability"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Net VAT liability (output VAT minus input VAT)"
+
+    def formula(firm, period, parameters):
+        output_vat = firm("firm_vat_on_sales", period)
+        input_vat = firm("firm_vat_on_purchases", period)
+
+        return output_vat - input_vat
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_reduced_rated_supplies.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_reduced_rated_supplies.py
new file mode 100644
index 000000000..50cbf18e5
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_reduced_rated_supplies.py
@@ -0,0 +1,11 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_reduced_rated_supplies(Variable):
+    value_type = float
+    entity = Firm
+    label = "Reduced-rated supplies"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Value of supplies subject to reduced VAT rate (5%)"
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_standard_rated_supplies.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_standard_rated_supplies.py
new file mode 100644
index 000000000..c2b7eeee0
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_standard_rated_supplies.py
@@ -0,0 +1,11 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_standard_rated_supplies(Variable):
+    value_type = float
+    entity = Firm
+    label = "Standard-rated supplies"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Value of supplies subject to standard VAT rate (20%)"
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_liability_calculated.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_liability_calculated.py
new file mode 100644
index 000000000..2e5b4c5ed
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_liability_calculated.py
@@ -0,0 +1,16 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_vat_liability_calculated(Variable):
+    value_type = float
+    entity = Firm
+    label = "Calculated VAT liability"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Calculated VAT liability based on supplies and parameters"
+
+    def formula(firm, period, parameters):
+        # This calculates VAT based on supplies and rates
+        # Compare with vat_liability_k from the dataset
+        return firm("firm_net_vat_liability", period)
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_purchases.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_purchases.py
new file mode 100644
index 000000000..c4e5dbc77
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_purchases.py
@@ -0,0 +1,11 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_vat_on_purchases(Variable):
+    value_type = float
+    entity = Firm
+    label = "VAT on purchases"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Total VAT paid on firm's purchases (input VAT)"
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_sales.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_sales.py
new file mode 100644
index 000000000..43bbc1fe6
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_on_sales.py
@@ -0,0 +1,26 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_vat_on_sales(Variable):
+    value_type = float
+    entity = Firm
+    label = "VAT on sales"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Total VAT charged on firm's sales (output VAT)"
+
+    def formula(firm, period, parameters):
+        # Only calculate for VAT registered firms
+        registered = firm("firm_vat_registered", period)
+
+        p = parameters(period).gov.hmrc.vat
+
+        standard_supplies = firm("firm_standard_rated_supplies", period)
+        reduced_supplies = firm("firm_reduced_rated_supplies", period)
+
+        standard_vat = standard_supplies * p.standard_rate
+        reduced_vat = reduced_supplies * p.reduced_rate
+        # Zero-rated supplies have 0% VAT by definition
+
+        return where(registered, standard_vat + reduced_vat, 0)
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_registered.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_registered.py
new file mode 100644
index 000000000..a9c4e9d7f
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_vat_registered.py
@@ -0,0 +1,20 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_vat_registered(Variable):
+    value_type = bool
+    entity = Firm
+    label = "VAT registered"
+    definition_period = YEAR
+    documentation = (
+        "Whether the firm is registered for VAT based on turnover threshold"
+    )
+
+    def formula(firm, period, parameters):
+        # Use annual_turnover_k from our existing firm variables
+        # Convert from thousands to pounds
+        turnover = firm("annual_turnover_k", period) * 1000
+        threshold = parameters(period).gov.hmrc.vat.registration_threshold
+
+        return turnover > threshold
diff --git a/policyengine_uk/variables_firm/gov/hmrc/vat/firm_zero_rated_supplies.py b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_zero_rated_supplies.py
new file mode 100644
index 000000000..f07844303
--- /dev/null
+++ b/policyengine_uk/variables_firm/gov/hmrc/vat/firm_zero_rated_supplies.py
@@ -0,0 +1,11 @@
+from policyengine_uk.model_api import *
+from policyengine_uk.entities import Firm
+
+
+class firm_zero_rated_supplies(Variable):
+    value_type = float
+    entity = Firm
+    label = "Zero-rated supplies"
+    definition_period = YEAR
+    unit = GBP
+    documentation = "Value of supplies subject to zero VAT rate (0%)"
diff --git a/policyengine_uk/variables_firm/input/business_group.py b/policyengine_uk/variables_firm/input/business_group.py
new file mode 100644
index 000000000..3da3d77ed
--- /dev/null
+++ b/policyengine_uk/variables_firm/input/business_group.py
@@ -0,0 +1,13 @@
+from policyengine_uk.model_api import *
+
+label = "Business Group"
+description = "Business group variables."
+
+
+class business_group_id(Variable):
+    value_type = int
+    entity = BusinessGroup
+    label = "business group ID"
+    documentation = "Unique identifier for each business group"
+    definition_period = YEAR
+    quantity_type = STOCK
diff --git a/policyengine_uk/variables_firm/input/firm.py b/policyengine_uk/variables_firm/input/firm.py
new file mode 100644
index 000000000..221de3a7a
--- /dev/null
+++ b/policyengine_uk/variables_firm/input/firm.py
@@ -0,0 +1,133 @@
+from policyengine_uk.model_api import *
+
+label = "Firm"
+description = "Business firm variables from firm dataset."
+
+
+class firm_id(Variable):
+    value_type = int
+    entity = Firm
+    label = "firm ID"
+    documentation = "Unique identifier for each firm"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class firm_sector_id(Variable):
+    value_type = int
+    entity = Firm
+    label = "firm sector ID"
+    documentation = "Identifier linking firm to its sector"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class firm_business_group_id(Variable):
+    value_type = int
+    entity = Firm
+    label = "firm business group ID"
+    documentation = "Identifier linking firm to its business group"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class year(Variable):
+    value_type = int
+    entity = Firm
+    label = "year"
+    documentation = "Year of the data"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class firm_weight(Variable):
+    value_type = float
+    entity = Firm
+    label = "firm weight"
+    documentation = "Statistical weight for firm in population"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class sic_code(Variable):
+    value_type = str
+    entity = Firm
+    label = "SIC code"
+    documentation = "Standard Industrial Classification code"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class annual_turnover_k(Variable):
+    value_type = float
+    entity = Firm
+    label = "annual turnover (thousands)"
+    documentation = "Annual turnover in thousands of pounds"
+    definition_period = YEAR
+    unit = GBP
+    quantity_type = FLOW
+
+
+class annual_input_k(Variable):
+    value_type = float
+    entity = Firm
+    label = "annual input (thousands)"
+    documentation = "Annual input costs in thousands of pounds"
+    definition_period = YEAR
+    unit = GBP
+    quantity_type = FLOW
+
+
+class vat_liability_k(Variable):
+    value_type = float
+    entity = Firm
+    label = "VAT liability (thousands)"
+    documentation = "VAT liability in thousands of pounds"
+    definition_period = YEAR
+    unit = GBP
+    quantity_type = FLOW
+
+
+class employment(Variable):
+    value_type = int
+    entity = Firm
+    label = "employment"
+    documentation = "Number of employees"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class vat_registered(Variable):
+    value_type = bool
+    entity = Firm
+    label = "VAT registered"
+    documentation = "Whether the firm is registered for VAT"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class hmrc_band(Variable):
+    value_type = str
+    entity = Firm
+    label = "HMRC band"
+    documentation = "HMRC size band classification"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class employment_band(Variable):
+    value_type = str
+    entity = Firm
+    label = "employment band"
+    documentation = "Employment size band classification"
+    definition_period = YEAR
+    quantity_type = STOCK
+
+
+class sic_numeric(Variable):
+    value_type = int
+    entity = Firm
+    label = "SIC numeric"
+    documentation = "Numeric version of SIC code"
+    definition_period = YEAR
+    quantity_type = STOCK
diff --git a/policyengine_uk/variables_firm/input/sector.py b/policyengine_uk/variables_firm/input/sector.py
new file mode 100644
index 000000000..e33a7678a
--- /dev/null
+++ b/policyengine_uk/variables_firm/input/sector.py
@@ -0,0 +1,13 @@
+from policyengine_uk.model_api import *
+
+label = "Sector"
+description = "Economic sector variables."
+
+
+class sector_id(Variable):
+    value_type = int
+    entity = Sector
+    label = "sector ID"
+    documentation = "Unique identifier for each sector"
+    definition_period = YEAR
+    quantity_type = STOCK