diff --git a/docs/misc/changelog.rst b/docs/misc/changelog.rst
index e614819..4bc5907 100644
--- a/docs/misc/changelog.rst
+++ b/docs/misc/changelog.rst
@@ -27,6 +27,7 @@ Deprecations:
 Others:
 ^^^^^^^
 - Add more issue templates
+- Add signatures to callable type annotations (@erniejunior)
 - Improve error message in ``NatureCNN``
 
 Documentation:
diff --git a/stable_baselines3/a2c/a2c.py b/stable_baselines3/a2c/a2c.py
index ee25ee2..42400c5 100644
--- a/stable_baselines3/a2c/a2c.py
+++ b/stable_baselines3/a2c/a2c.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, Optional, Type, Union
+from typing import Any, Dict, Optional, Type, Union
 
 import torch as th
 from gym import spaces
@@ -7,7 +7,7 @@ from torch.nn import functional as F
 from stable_baselines3.common import logger
 from stable_baselines3.common.on_policy_algorithm import OnPolicyAlgorithm
 from stable_baselines3.common.policies import ActorCriticPolicy
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import explained_variance
 
 
@@ -55,7 +55,7 @@ class A2C(OnPolicyAlgorithm):
         self,
         policy: Union[str, Type[ActorCriticPolicy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 7e-4,
+        learning_rate: Union[float, LearningRateSchedule] = 7e-4,
         n_steps: int = 5,
         gamma: float = 0.99,
         gae_lambda: float = 1.0,
diff --git a/stable_baselines3/common/base_class.py b/stable_baselines3/common/base_class.py
index f33b36f..58bdf88 100644
--- a/stable_baselines3/common/base_class.py
+++ b/stable_baselines3/common/base_class.py
@@ -5,7 +5,7 @@ import pathlib
 import time
 from abc import ABC, abstractmethod
 from collections import deque
-from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, Iterable, List, Optional, Tuple, Type, Union
 
 import gym
 import numpy as np
@@ -18,7 +18,7 @@ from stable_baselines3.common.noise import ActionNoise
 from stable_baselines3.common.policies import BasePolicy, get_policy_from_name
 from stable_baselines3.common.preprocessing import is_image_space, is_image_space_channels_first
 from stable_baselines3.common.save_util import load_from_zip_file, recursive_getattr, recursive_setattr, save_to_zip_file
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import (
     check_for_correct_spaces,
     get_device,
@@ -89,7 +89,7 @@ class BaseAlgorithm(ABC):
         policy: Type[BasePolicy],
         env: Union[GymEnv, str, None],
         policy_base: Type[BasePolicy],
-        learning_rate: Union[float, Callable],
+        learning_rate: Union[float, LearningRateSchedule],
         policy_kwargs: Dict[str, Any] = None,
         tensorboard_log: Optional[str] = None,
         verbose: int = 0,
@@ -129,7 +129,7 @@ class BaseAlgorithm(ABC):
         self.policy = None
         self.learning_rate = learning_rate
         self.tensorboard_log = tensorboard_log
-        self.lr_schedule = None  # type: Optional[Callable]
+        self.lr_schedule = None  # type: Optional[LearningRateSchedule]
         self._last_obs = None  # type: Optional[np.ndarray]
         self._last_dones = None  # type: Optional[np.ndarray]
         # When using VecNormalize:
diff --git a/stable_baselines3/common/callbacks.py b/stable_baselines3/common/callbacks.py
index 872aed1..27d7748 100644
--- a/stable_baselines3/common/callbacks.py
+++ b/stable_baselines3/common/callbacks.py
@@ -248,7 +248,7 @@ class ConvertCallback(BaseCallback):
     :param verbose:
     """
 
-    def __init__(self, callback: Callable, verbose: int = 0):
+    def __init__(self, callback: Callable[[Dict[str, Any], Dict[str, Any]], bool], verbose: int = 0):
         super(ConvertCallback, self).__init__(verbose)
         self.callback = callback
 
diff --git a/stable_baselines3/common/env_util.py b/stable_baselines3/common/env_util.py
index 8a9985e..0458b30 100644
--- a/stable_baselines3/common/env_util.py
+++ b/stable_baselines3/common/env_util.py
@@ -14,7 +14,7 @@ def make_vec_env(
     seed: Optional[int] = None,
     start_index: int = 0,
     monitor_dir: Optional[str] = None,
-    wrapper_class: Optional[Callable] = None,
+    wrapper_class: Optional[Callable[[gym.Env], gym.Env]] = None,
     env_kwargs: Optional[Dict[str, Any]] = None,
     vec_env_cls: Optional[Type[Union[DummyVecEnv, SubprocVecEnv]]] = None,
     vec_env_kwargs: Optional[Dict[str, Any]] = None,
diff --git a/stable_baselines3/common/evaluation.py b/stable_baselines3/common/evaluation.py
index 8b89b00..0ed40e4 100644
--- a/stable_baselines3/common/evaluation.py
+++ b/stable_baselines3/common/evaluation.py
@@ -1,4 +1,4 @@
-from typing import Callable, List, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
 import gym
 import numpy as np
@@ -13,7 +13,7 @@ def evaluate_policy(
     n_eval_episodes: int = 10,
     deterministic: bool = True,
     render: bool = False,
-    callback: Optional[Callable] = None,
+    callback: Optional[Callable[[Dict[str, Any], Dict[str, Any]], None]] = None,
     reward_threshold: Optional[float] = None,
     return_episode_rewards: bool = False,
 ) -> Union[Tuple[float, float], Tuple[List[float], List[int]]]:
@@ -28,7 +28,7 @@ def evaluate_policy(
     :param deterministic: Whether to use deterministic or stochastic actions
     :param render: Whether to render the environment or not
     :param callback: callback function to do additional checks,
-        called after each step.
+        called after each step. Gets locals() and globals() passed as parameters.
     :param reward_threshold: Minimum expected reward per episode,
         this will raise an error if the performance is not met
     :param return_episode_rewards: If True, a list of reward per episode
diff --git a/stable_baselines3/common/off_policy_algorithm.py b/stable_baselines3/common/off_policy_algorithm.py
index a536417..37662a6 100644
--- a/stable_baselines3/common/off_policy_algorithm.py
+++ b/stable_baselines3/common/off_policy_algorithm.py
@@ -2,7 +2,7 @@ import io
 import pathlib
 import time
 import warnings
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, Optional, Tuple, Type, Union
 
 import gym
 import numpy as np
@@ -15,7 +15,7 @@ from stable_baselines3.common.callbacks import BaseCallback
 from stable_baselines3.common.noise import ActionNoise
 from stable_baselines3.common.policies import BasePolicy
 from stable_baselines3.common.save_util import load_from_pkl, save_to_pkl
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback, RolloutReturn
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback, RolloutReturn
 from stable_baselines3.common.utils import safe_mean
 from stable_baselines3.common.vec_env import VecEnv
 
@@ -76,7 +76,7 @@ class OffPolicyAlgorithm(BaseAlgorithm):
         policy: Type[BasePolicy],
         env: Union[GymEnv, str],
         policy_base: Type[BasePolicy],
-        learning_rate: Union[float, Callable],
+        learning_rate: Union[float, LearningRateSchedule],
         buffer_size: int = int(1e6),
         learning_starts: int = 100,
         batch_size: int = 256,
@@ -192,7 +192,7 @@ class OffPolicyAlgorithm(BaseAlgorithm):
         self,
         total_timesteps: int,
         eval_env: Optional[GymEnv],
-        callback: Union[None, Callable, List[BaseCallback], BaseCallback] = None,
+        callback: MaybeCallback = None,
         eval_freq: int = 10000,
         n_eval_episodes: int = 5,
         log_path: Optional[str] = None,
diff --git a/stable_baselines3/common/on_policy_algorithm.py b/stable_baselines3/common/on_policy_algorithm.py
index 6cd5dbf..527cb9d 100644
--- a/stable_baselines3/common/on_policy_algorithm.py
+++ b/stable_baselines3/common/on_policy_algorithm.py
@@ -1,5 +1,5 @@
 import time
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, List, Optional, Tuple, Type, Union
 
 import gym
 import numpy as np
@@ -10,7 +10,7 @@ from stable_baselines3.common.base_class import BaseAlgorithm
 from stable_baselines3.common.buffers import RolloutBuffer
 from stable_baselines3.common.callbacks import BaseCallback
 from stable_baselines3.common.policies import ActorCriticPolicy
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import safe_mean
 from stable_baselines3.common.vec_env import VecEnv
 
@@ -52,7 +52,7 @@ class OnPolicyAlgorithm(BaseAlgorithm):
         self,
         policy: Union[str, Type[ActorCriticPolicy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable],
+        learning_rate: Union[float, LearningRateSchedule],
         n_steps: int,
         gamma: float,
         gae_lambda: float,
diff --git a/stable_baselines3/common/policies.py b/stable_baselines3/common/policies.py
index d07f115..64eefd2 100644
--- a/stable_baselines3/common/policies.py
+++ b/stable_baselines3/common/policies.py
@@ -21,6 +21,7 @@ from stable_baselines3.common.distributions import (
 )
 from stable_baselines3.common.preprocessing import get_action_dim, is_image_space, preprocess_obs
 from stable_baselines3.common.torch_layers import BaseFeaturesExtractor, FlattenExtractor, MlpExtractor, NatureCNN, create_mlp
+from stable_baselines3.common.type_aliases import LearningRateSchedule
 from stable_baselines3.common.utils import get_device, is_vectorized_observation
 from stable_baselines3.common.vec_env import VecTransposeImage
 from stable_baselines3.common.vec_env.obs_dict_wrapper import ObsDictWrapper
@@ -364,7 +365,7 @@ class ActorCriticPolicy(BasePolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable[[float], float],
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[List[Union[int, Dict[str, List[int]]]]] = None,
         activation_fn: Type[nn.Module] = nn.Tanh,
         ortho_init: bool = True,
@@ -479,7 +480,7 @@ class ActorCriticPolicy(BasePolicy):
             self.features_dim, net_arch=self.net_arch, activation_fn=self.activation_fn, device=self.device
         )
 
-    def _build(self, lr_schedule: Callable[[float], float]) -> None:
+    def _build(self, lr_schedule: LearningRateSchedule) -> None:
         """
         Create the networks and the optimizer.
 
@@ -662,7 +663,7 @@ class ActorCriticCnnPolicy(ActorCriticPolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[List[Union[int, Dict[str, List[int]]]]] = None,
         activation_fn: Type[nn.Module] = nn.Tanh,
         ortho_init: bool = True,
diff --git a/stable_baselines3/common/sb2_compat/rmsprop_tf_like.py b/stable_baselines3/common/sb2_compat/rmsprop_tf_like.py
index 758079f..ba70a5f 100644
--- a/stable_baselines3/common/sb2_compat/rmsprop_tf_like.py
+++ b/stable_baselines3/common/sb2_compat/rmsprop_tf_like.py
@@ -74,7 +74,7 @@ class RMSpropTFLike(Optimizer):
             group.setdefault("centered", False)
 
     @torch.no_grad()
-    def step(self, closure: Optional[Callable] = None) -> Optional[torch.Tensor]:
+    def step(self, closure: Optional[Callable[[], None]] = None) -> Optional[torch.Tensor]:
         """Performs a single optimization step.
 
         :param closure: A closure that reevaluates the model
diff --git a/stable_baselines3/common/type_aliases.py b/stable_baselines3/common/type_aliases.py
index 0d95d00..1577423 100644
--- a/stable_baselines3/common/type_aliases.py
+++ b/stable_baselines3/common/type_aliases.py
@@ -15,6 +15,7 @@ GymStepReturn = Tuple[GymObs, float, bool, Dict]
 TensorDict = Dict[str, th.Tensor]
 OptimizerStateDict = Dict[str, Any]
 MaybeCallback = Union[None, Callable, List[callbacks.BaseCallback], callbacks.BaseCallback]
+LearningRateSchedule = Callable[[float], float]
 
 
 class RolloutBufferSamples(NamedTuple):
diff --git a/stable_baselines3/common/utils.py b/stable_baselines3/common/utils.py
index 2f02ed7..5b1043e 100644
--- a/stable_baselines3/common/utils.py
+++ b/stable_baselines3/common/utils.py
@@ -16,7 +16,7 @@ except ImportError:
     SummaryWriter = None
 
 from stable_baselines3.common import logger
-from stable_baselines3.common.type_aliases import GymEnv
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule
 
 
 def set_random_seed(seed: int, using_cuda: bool = False) -> None:
@@ -70,7 +70,7 @@ def update_learning_rate(optimizer: th.optim.Optimizer, learning_rate: float) ->
         param_group["lr"] = learning_rate
 
 
-def get_schedule_fn(value_schedule: Union[Callable, float]) -> Callable:
+def get_schedule_fn(value_schedule: Union[LearningRateSchedule, float, int]) -> LearningRateSchedule:
     """
     Transform (if needed) learning rate and clip range (for PPO)
     to callable.
@@ -88,7 +88,7 @@ def get_schedule_fn(value_schedule: Union[Callable, float]) -> Callable:
     return value_schedule
 
 
-def get_linear_fn(start: float, end: float, end_fraction: float) -> Callable:
+def get_linear_fn(start: float, end: float, end_fraction: float) -> LearningRateSchedule:
     """
     Create a function that interpolates linearly between start and end
     between ``progress_remaining`` = 1 and ``progress_remaining`` = ``end_fraction``.
@@ -112,7 +112,7 @@ def get_linear_fn(start: float, end: float, end_fraction: float) -> Callable:
     return func
 
 
-def constant_fn(val: float) -> Callable:
+def constant_fn(val: float) -> LearningRateSchedule:
     """
     Create a function that returns a constant
     It is useful for learning rate schedule (to avoid code duplication)
diff --git a/stable_baselines3/ddpg/ddpg.py b/stable_baselines3/ddpg/ddpg.py
index 8acd0f8..d4af6cc 100644
--- a/stable_baselines3/ddpg/ddpg.py
+++ b/stable_baselines3/ddpg/ddpg.py
@@ -1,10 +1,10 @@
-from typing import Any, Callable, Dict, Optional, Type, Union
+from typing import Any, Dict, Optional, Type, Union
 
 import torch as th
 
 from stable_baselines3.common.noise import ActionNoise
 from stable_baselines3.common.off_policy_algorithm import OffPolicyAlgorithm
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.td3.policies import TD3Policy
 from stable_baselines3.td3.td3 import TD3
 
@@ -55,7 +55,7 @@ class DDPG(TD3):
         self,
         policy: Union[str, Type[TD3Policy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 1e-3,
+        learning_rate: Union[float, LearningRateSchedule] = 1e-3,
         buffer_size: int = int(1e6),
         learning_starts: int = 100,
         batch_size: int = 100,
diff --git a/stable_baselines3/dqn/dqn.py b/stable_baselines3/dqn/dqn.py
index 7a35566..648475e 100644
--- a/stable_baselines3/dqn/dqn.py
+++ b/stable_baselines3/dqn/dqn.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, List, Optional, Tuple, Type, Union
 
 import numpy as np
 import torch as th
@@ -6,7 +6,7 @@ from torch.nn import functional as F
 
 from stable_baselines3.common import logger
 from stable_baselines3.common.off_policy_algorithm import OffPolicyAlgorithm
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import get_linear_fn, polyak_update
 from stable_baselines3.dqn.policies import DQNPolicy
 
@@ -59,7 +59,7 @@ class DQN(OffPolicyAlgorithm):
         self,
         policy: Union[str, Type[DQNPolicy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 1e-4,
+        learning_rate: Union[float, LearningRateSchedule] = 1e-4,
         buffer_size: int = 1000000,
         learning_starts: int = 50000,
         batch_size: Optional[int] = 32,
diff --git a/stable_baselines3/dqn/policies.py b/stable_baselines3/dqn/policies.py
index 7416f02..35e6581 100644
--- a/stable_baselines3/dqn/policies.py
+++ b/stable_baselines3/dqn/policies.py
@@ -6,6 +6,7 @@ from torch import nn
 
 from stable_baselines3.common.policies import BasePolicy, register_policy
 from stable_baselines3.common.torch_layers import BaseFeaturesExtractor, FlattenExtractor, NatureCNN, create_mlp
+from stable_baselines3.common.type_aliases import LearningRateSchedule
 
 
 class QNetwork(BasePolicy):
@@ -103,7 +104,7 @@ class DQNPolicy(BasePolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[List[int]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         features_extractor_class: Type[BaseFeaturesExtractor] = FlattenExtractor,
@@ -142,7 +143,7 @@ class DQNPolicy(BasePolicy):
         self.q_net, self.q_net_target = None, None
         self._build(lr_schedule)
 
-    def _build(self, lr_schedule: Callable) -> None:
+    def _build(self, lr_schedule: LearningRateSchedule) -> None:
         """
         Create the network and the optimizer.
 
@@ -210,7 +211,7 @@ class CnnPolicy(DQNPolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[List[int]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         features_extractor_class: Type[BaseFeaturesExtractor] = NatureCNN,
diff --git a/stable_baselines3/ppo/ppo.py b/stable_baselines3/ppo/ppo.py
index 4ea6253..b9ae9fb 100644
--- a/stable_baselines3/ppo/ppo.py
+++ b/stable_baselines3/ppo/ppo.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, Optional, Type, Union
+from typing import Any, Dict, Optional, Type, Union
 
 import numpy as np
 import torch as th
@@ -8,7 +8,7 @@ from torch.nn import functional as F
 from stable_baselines3.common import logger
 from stable_baselines3.common.on_policy_algorithm import OnPolicyAlgorithm
 from stable_baselines3.common.policies import ActorCriticPolicy
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import explained_variance, get_schedule_fn
 
 
@@ -66,7 +66,7 @@ class PPO(OnPolicyAlgorithm):
         self,
         policy: Union[str, Type[ActorCriticPolicy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 3e-4,
+        learning_rate: Union[float, LearningRateSchedule] = 3e-4,
         n_steps: int = 2048,
         batch_size: Optional[int] = 64,
         n_epochs: int = 10,
diff --git a/stable_baselines3/sac/policies.py b/stable_baselines3/sac/policies.py
index c79d679..bdc8b92 100644
--- a/stable_baselines3/sac/policies.py
+++ b/stable_baselines3/sac/policies.py
@@ -14,6 +14,7 @@ from stable_baselines3.common.torch_layers import (
     create_mlp,
     get_actor_critic_arch,
 )
+from stable_baselines3.common.type_aliases import LearningRateSchedule
 
 # CAP the standard deviation of the actor
 LOG_STD_MAX = 2
@@ -227,7 +228,7 @@ class SACPolicy(BasePolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[Union[List[int], Dict[str, List[int]]]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         use_sde: bool = False,
@@ -294,7 +295,7 @@ class SACPolicy(BasePolicy):
 
         self._build(lr_schedule)
 
-    def _build(self, lr_schedule: Callable) -> None:
+    def _build(self, lr_schedule: LearningRateSchedule) -> None:
         self.actor = self.make_actor()
         self.actor.optimizer = self.optimizer_class(self.actor.parameters(), lr=lr_schedule(1), **self.optimizer_kwargs)
 
@@ -397,7 +398,7 @@ class CnnPolicy(SACPolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[Union[List[int], Dict[str, List[int]]]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         use_sde: bool = False,
diff --git a/stable_baselines3/sac/sac.py b/stable_baselines3/sac/sac.py
index 785cc9d..d52cf10 100644
--- a/stable_baselines3/sac/sac.py
+++ b/stable_baselines3/sac/sac.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, List, Optional, Tuple, Type, Union
 
 import numpy as np
 import torch as th
@@ -7,7 +7,7 @@ from torch.nn import functional as F
 from stable_baselines3.common import logger
 from stable_baselines3.common.noise import ActionNoise
 from stable_baselines3.common.off_policy_algorithm import OffPolicyAlgorithm
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import polyak_update
 from stable_baselines3.sac.policies import SACPolicy
 
@@ -74,7 +74,7 @@ class SAC(OffPolicyAlgorithm):
         self,
         policy: Union[str, Type[SACPolicy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 3e-4,
+        learning_rate: Union[float, LearningRateSchedule] = 3e-4,
         buffer_size: int = int(1e6),
         learning_starts: int = 100,
         batch_size: int = 256,
diff --git a/stable_baselines3/td3/policies.py b/stable_baselines3/td3/policies.py
index 0083a49..ed5669b 100644
--- a/stable_baselines3/td3/policies.py
+++ b/stable_baselines3/td3/policies.py
@@ -13,6 +13,7 @@ from stable_baselines3.common.torch_layers import (
     create_mlp,
     get_actor_critic_arch,
 )
+from stable_baselines3.common.type_aliases import LearningRateSchedule
 
 
 class Actor(BasePolicy):
@@ -108,7 +109,7 @@ class TD3Policy(BasePolicy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[Union[List[int], Dict[str, List[int]]]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         features_extractor_class: Type[BaseFeaturesExtractor] = FlattenExtractor,
@@ -163,7 +164,7 @@ class TD3Policy(BasePolicy):
 
         self._build(lr_schedule)
 
-    def _build(self, lr_schedule: Callable) -> None:
+    def _build(self, lr_schedule: LearningRateSchedule) -> None:
         # Create actor and target
         # the features extractor should not be shared
         self.actor = self.make_actor(features_extractor=None)
@@ -252,7 +253,7 @@ class CnnPolicy(TD3Policy):
         self,
         observation_space: gym.spaces.Space,
         action_space: gym.spaces.Space,
-        lr_schedule: Callable,
+        lr_schedule: LearningRateSchedule,
         net_arch: Optional[Union[List[int], Dict[str, List[int]]]] = None,
         activation_fn: Type[nn.Module] = nn.ReLU,
         features_extractor_class: Type[BaseFeaturesExtractor] = NatureCNN,
diff --git a/stable_baselines3/td3/td3.py b/stable_baselines3/td3/td3.py
index a1186ec..a0e5004 100644
--- a/stable_baselines3/td3/td3.py
+++ b/stable_baselines3/td3/td3.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, List, Optional, Tuple, Type, Union
 
 import numpy as np
 import torch as th
@@ -7,7 +7,7 @@ from torch.nn import functional as F
 from stable_baselines3.common import logger
 from stable_baselines3.common.noise import ActionNoise
 from stable_baselines3.common.off_policy_algorithm import OffPolicyAlgorithm
-from stable_baselines3.common.type_aliases import GymEnv, MaybeCallback
+from stable_baselines3.common.type_aliases import GymEnv, LearningRateSchedule, MaybeCallback
 from stable_baselines3.common.utils import polyak_update
 from stable_baselines3.td3.policies import TD3Policy
 
@@ -62,7 +62,7 @@ class TD3(OffPolicyAlgorithm):
         self,
         policy: Union[str, Type[TD3Policy]],
         env: Union[GymEnv, str],
-        learning_rate: Union[float, Callable] = 1e-3,
+        learning_rate: Union[float, LearningRateSchedule] = 1e-3,
         buffer_size: int = int(1e6),
         learning_starts: int = 100,
         batch_size: int = 100,