diff --git a/docs/src/format.md b/docs/src/format.md
index ce5fc2a..7707b48 100644
--- a/docs/src/format.md
+++ b/docs/src/format.md
@@ -90,6 +90,7 @@ This section describes all generators in the system, including thermal units, re
 | `Initial power (MW)`  | Amount of power the generator at time step `-1`, immediately before the planning horizon starts. | Required | N
 | `Must run?`               | If `true`, the generator should be committed, even if that is not economical (Boolean). | `false` | Y
 | `Reserve eligibility` | List of reserve products this generator is eligibe to provide. By default, the generator is not eligible to provide any reserves. | `[]` | N
+| `Commitment status` | List of commitment status over the time horizon. At time `t`, if `true`, the generator must be commited at that time period; if `false`, the generator must not be commited at that time period. If `null` at time `t`, the generator's commitment status is then decided by the model. By default, the status is a list of `null` values. | `[null]` | Y
 
 #### Profiled Units
 
@@ -151,7 +152,8 @@ Note that this curve also specifies the production limits. Specifically, the fir
             "Production cost curve ($)": [0.0, 0.0],
             "Initial status (h)": -100,
             "Initial power (MW)": 0,
-            "Reserve eligibility": ["r1", "r2"]
+            "Reserve eligibility": ["r1", "r2"],
+            "Commitment status": [true, false, null, true]
         },
         "gen3": {
             "Bus": "b6",
diff --git a/src/instance/read.jl b/src/instance/read.jl
index 1fda33b..024e478 100644
--- a/src/instance/read.jl
+++ b/src/instance/read.jl
@@ -282,6 +282,12 @@ function _from_json(json; repair = true)::UnitCommitmentScenario
                 initial_status *= time_multiplier
             end
 
+            # Read commitment status 
+            commitment_status = scalar(
+                dict["Commitment status"],
+                default = Vector{Union{Bool,Nothing}}(nothing, T),
+            )
+
             unit = ThermalUnit(
                 unit_name,
                 bus,
@@ -302,6 +308,7 @@ function _from_json(json; repair = true)::UnitCommitmentScenario
                 initial_power,
                 startup_categories,
                 unit_reserves,
+                commitment_status,
             )
             push!(bus.thermal_units, unit)
             for r in unit_reserves
diff --git a/src/instance/structs.jl b/src/instance/structs.jl
index bdf729f..15dfef4 100644
--- a/src/instance/structs.jl
+++ b/src/instance/structs.jl
@@ -47,6 +47,7 @@ mutable struct ThermalUnit
     initial_power::Union{Float64,Nothing}
     startup_categories::Vector{StartupCategory}
     reserves::Vector{Reserve}
+    commitment_status::Vector{Union{Bool,Nothing}}
 end
 
 mutable struct TransmissionLine
diff --git a/src/model/formulations/base/unit.jl b/src/model/formulations/base/unit.jl
index 06b18a2..83cf543 100644
--- a/src/model/formulations/base/unit.jl
+++ b/src/model/formulations/base/unit.jl
@@ -61,6 +61,7 @@ function _add_unit_dispatch!(
         sc,
     )
     _add_startup_shutdown_limit_eqs!(model, g, sc)
+    _add_commitment_status_eqs!(model, g, sc)
     return
 end
 
@@ -270,6 +271,26 @@ function _add_min_uptime_downtime_eqs!(
     end
 end
 
+function _add_commitment_status_eqs!(
+    model::JuMP.Model,
+    g::ThermalUnit,
+    sc::UnitCommitmentScenario,
+)::Nothing
+    is_on = model[:is_on]
+    T = model[:instance].time
+    eq_commitment_status = _init(model, :eq_commitment_status)
+    for t in 1:T
+        # Fix commitment status
+        if g.commitment_status[t] !== nothing
+            eq_commitment_status[sc.name, g.name, t] = @constraint(
+                model,
+                is_on[g.name, t] == (g.commitment_status[t] ? 1.0 : 0.0)
+            )
+        end
+    end
+    return
+end
+
 function _add_net_injection_eqs!(
     model::JuMP.Model,
     g::ThermalUnit,
diff --git a/test/instance/read_test.jl b/test/instance/read_test.jl
index 78c3d78..ccde032 100644
--- a/test/instance/read_test.jl
+++ b/test/instance/read_test.jl
@@ -153,3 +153,14 @@ end
     @test second_pu.capacity == [120.0 for t in 1:4]
     @test sc.profiled_units_by_name["g8"].name == "g8"
 end
+
+@testset "read_benchmark commitmemt-status" begin
+    instance = UnitCommitment.read("$FIXTURES/case14-fixed-status.json.gz")
+    sc = instance.scenarios[1]
+
+    @test sc.thermal_units[1].commitment_status == [nothing for t in 1:4]
+    @test sc.thermal_units[2].commitment_status == [true for t in 1:4]
+    @test sc.thermal_units[4].commitment_status == [false for t in 1:4]
+    @test sc.thermal_units[6].commitment_status ==
+          [false, nothing, true, nothing]
+end