diff --git a/src/ComputingTasks.cc b/src/ComputingTasks.cc
index e05e9fa2bc6e5b383cdf9993184ce88f5ee8ece8..4b1b758967c479e7bc3bdd167fb3fbf8a87b77c0 100644
--- a/src/ComputingTasks.cc
+++ b/src/ComputingTasks.cc
@@ -3713,8 +3713,7 @@ SvarGlobalIdentificationCheckStatement::writeJsonOutput(ostream& output) const
   output << R"({"statementName": "svar_global_identification"})";
 }
 
-SetTimeStatement::SetTimeStatement(OptionsList options_list_arg) :
-    options_list {move(options_list_arg)}
+SetTimeStatement::SetTimeStatement(string period_arg) : period {move(period_arg)}
 {
 }
 
@@ -3722,19 +3721,13 @@ void
 SetTimeStatement::writeOutput(ostream& output, [[maybe_unused]] const string& basename,
                               [[maybe_unused]] bool minimal_workspace) const
 {
-  options_list.writeOutput(output);
+  output << "options_.initial_period = " << period << endl;
 }
 
 void
 SetTimeStatement::writeJsonOutput(ostream& output) const
 {
-  output << R"({"statementName": "set_time")";
-  if (!options_list.empty())
-    {
-      output << ", ";
-      options_list.writeJsonOutput(output);
-    }
-  output << "}";
+  output << R"({"statementName": "set_time", "period": ")" << period << R"("})";
 }
 
 EstimationDataStatement::EstimationDataStatement(OptionsList options_list_arg) :
diff --git a/src/ComputingTasks.hh b/src/ComputingTasks.hh
index 747bb0a59306787e2d1e9bae842537a531814bac..2e4df64a6f732cc75e3495a801a66d360e8dec20 100644
--- a/src/ComputingTasks.hh
+++ b/src/ComputingTasks.hh
@@ -1007,10 +1007,10 @@ public:
 class SetTimeStatement : public Statement
 {
 private:
-  const OptionsList options_list;
+  const string period;
 
 public:
-  explicit SetTimeStatement(OptionsList options_list_arg);
+  explicit SetTimeStatement(string period_arg);
   void writeOutput(ostream& output, const string& basename, bool minimal_workspace) const override;
   void writeJsonOutput(ostream& output) const override;
 };
diff --git a/src/ParsingDriver.cc b/src/ParsingDriver.cc
index d8191d747312b767824290128c10a840420b1856..5afacaf79dfc6978378b96ded4b9ec9e6a286ca9 100644
--- a/src/ParsingDriver.cc
+++ b/src/ParsingDriver.cc
@@ -1739,11 +1739,9 @@ ParsingDriver::set_unit_root_vars()
 }
 
 void
-ParsingDriver::set_time(const string& arg)
+ParsingDriver::set_time(string period)
 {
-  option_date("initial_period", arg);
-  mod_file->addStatement(make_unique<SetTimeStatement>(move(options_list)));
-  options_list.clear();
+  mod_file->addStatement(make_unique<SetTimeStatement>(move(period)));
 }
 
 void
diff --git a/src/ParsingDriver.hh b/src/ParsingDriver.hh
index ffb2f4cb81c3d05b104e1f8f21e2e5b09bb7e8c5..132dee5834ba62b581abff2c6aab59e4d47e07ec 100644
--- a/src/ParsingDriver.hh
+++ b/src/ParsingDriver.hh
@@ -559,8 +559,8 @@ public:
   void osr_params_bounds();
   //! Add a line in an osr params block
   void add_osr_params_element();
-  //! Sets the frequency of the data
-  void set_time(const string& arg);
+  // Sets the initial period for estimation
+  void set_time(string period);
   //! Estimation Data
   void estimation_data();
   //! Sets the prior for a parameter