diff --git a/pkg/rpc/client/policy.go b/pkg/rpc/client/policy.go
index 26ff5ae9c..9f2f31d98 100644
--- a/pkg/rpc/client/policy.go
+++ b/pkg/rpc/client/policy.go
@@ -22,27 +22,46 @@ func (c *Client) GetMaxBlockSize() (int64, error) {
 
 // GetFeePerByte invokes `getFeePerByte` method on a native Policy contract.
 func (c *Client) GetFeePerByte() (int64, error) {
+	if !c.initDone {
+		return 0, errNetworkNotInitialized
+	}
 	return c.invokeNativePolicyMethod("getFeePerByte")
 }
 
 // GetExecFeeFactor invokes `getExecFeeFactor` method on a native Policy contract.
 func (c *Client) GetExecFeeFactor() (int64, error) {
+	if !c.initDone {
+		return 0, errNetworkNotInitialized
+	}
 	return c.invokeNativePolicyMethod("getExecFeeFactor")
 }
 
+// GetMaxNotValidBeforeDelta invokes `getMaxNotValidBeforeDelta` method on a native Notary contract.
+func (c *Client) GetMaxNotValidBeforeDelta() (int64, error) {
+	notaryHash, err := c.GetNativeContractHash(nativenames.Notary)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get native Notary hash: %w", err)
+	}
+	return c.invokeNativeGetMethod(notaryHash, "getMaxNotValidBeforeDelta")
+}
+
+// invokeNativePolicy method invokes Get* method on a native Policy contract.
 func (c *Client) invokeNativePolicyMethod(operation string) (int64, error) {
 	if !c.initDone {
 		return 0, errNetworkNotInitialized
 	}
-	result, err := c.InvokeFunction(c.cache.nativeHashes[nativenames.Policy], operation, []smartcontract.Parameter{}, nil)
+	return c.invokeNativeGetMethod(c.cache.nativeHashes[nativenames.Policy], operation)
+}
+
+func (c *Client) invokeNativeGetMethod(hash util.Uint160, operation string) (int64, error) {
+	result, err := c.InvokeFunction(hash, operation, []smartcontract.Parameter{}, nil)
 	if err != nil {
 		return 0, err
 	}
 	err = getInvocationError(result)
 	if err != nil {
-		return 0, fmt.Errorf("failed to invoke %s Policy method: %w", operation, err)
+		return 0, fmt.Errorf("failed to invoke %s method of native contract %s: %w", operation, hash.StringLE(), err)
 	}
-
 	return topIntFromStack(result.Stack)
 }
 
diff --git a/pkg/rpc/client/rpc_test.go b/pkg/rpc/client/rpc_test.go
index 30c849233..2e9674420 100644
--- a/pkg/rpc/client/rpc_test.go
+++ b/pkg/rpc/client/rpc_test.go
@@ -419,6 +419,18 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getExecFeeFactor": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetExecFeeFactor()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gasconsumed":"2007390","script":"EMAMDWdldEZlZVBlckJ5dGUMFJphpG7sl7iTBtfOgfFbRiCR0AkyQWJ9W1I=","stack":[{"type":"Integer","value":"1000"}],"tx":null}}`,
+			result: func(c *Client) interface{} {
+				return int64(1000)
+			},
+		},
+	},
 	"getMaxTransacctionsPerBlock": {
 		{
 			name: "positive",
@@ -443,6 +455,18 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getMaxNotValidBeforeDelta": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetMaxNotValidBeforeDelta()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gasconsumed":"2007390","script":"EMAMD2dldE1heEJsb2NrU2l6ZQwUmmGkbuyXuJMG186B8VtGIJHQCTJBYn1bUg==","stack":[{"type":"Integer","value":"262144"}],"tx":null}}`,
+			result: func(c *Client) interface{} {
+				return int64(262144)
+			},
+		},
+	},
 	"isBlocked": {
 		{
 			name: "positive",