diff --git a/matlab/utilities/dates/issubperiod.m b/matlab/utilities/dates/issubperiod.m
new file mode 100644
index 000000000..5f7a7560b
--- /dev/null
+++ b/matlab/utilities/dates/issubperiod.m
@@ -0,0 +1,24 @@
+function C = issubperiod(A,B)
+
+% Copyright (C) 2013 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+if isfreq(B)
+    C = all(isint(A)) && all(A>=1) && all(A<=B);
+else
+    error('issubperiod:: Second input argument must be equal to 1, 4, 12 or 52 (frequency)!')
+end
\ No newline at end of file