diff --git a/src/pytfe/models/comment.py b/src/pytfe/models/comment.py
index da2cd213..19cc25ca 100644
--- a/src/pytfe/models/comment.py
+++ b/src/pytfe/models/comment.py
@@ -10,4 +10,4 @@ class Comment(BaseModel):
     model_config = ConfigDict(populate_by_name=True, validate_by_name=True)
 
     id: str
-    body: str = Field(..., alias="body")
+    body: str = Field(default="", alias="body")
diff --git a/src/pytfe/models/cost_estimate.py b/src/pytfe/models/cost_estimate.py
index d1b6ff6b..4ae1c614 100644
--- a/src/pytfe/models/cost_estimate.py
+++ b/src/pytfe/models/cost_estimate.py
@@ -13,17 +13,17 @@ class CostEstimate(BaseModel):
     model_config = ConfigDict(populate_by_name=True, validate_by_name=True)
 
     id: str
-    delta_monthly_cost: str = Field(..., alias="delta-monthly-cost")
-    error_message: str = Field(..., alias="error-message")
-    matched_resources_count: int = Field(..., alias="matched-resources-count")
-    prior_monthly_cost: str = Field(..., alias="prior-monthly-cost")
-    proposed_monthly_cost: str = Field(..., alias="proposed-monthly-cost")
-    resources_count: int = Field(..., alias="resources-count")
-    status: CostEstimateStatus = Field(..., alias="status")
-    status_timestamps: CostEstimateStatusTimestamps = Field(
-        ..., alias="status-timestamps"
+    delta_monthly_cost: str = Field(default="", alias="delta-monthly-cost")
+    error_message: str = Field(default="", alias="error-message")
+    matched_resources_count: int = Field(default=0, alias="matched-resources-count")
+    prior_monthly_cost: str = Field(default="", alias="prior-monthly-cost")
+    proposed_monthly_cost: str = Field(default="", alias="proposed-monthly-cost")
+    resources_count: int = Field(default=0, alias="resources-count")
+    status: CostEstimateStatus | None = Field(default=None, alias="status")
+    status_timestamps: CostEstimateStatusTimestamps | None = Field(
+        default=None, alias="status-timestamps"
     )
-    unmatched_resources_count: int = Field(..., alias="unmatched-resources-count")
+    unmatched_resources_count: int = Field(default=0, alias="unmatched-resources-count")
 
 
 class CostEstimateStatus(str, Enum):