diff --git a/src/libecoPCR/ecofilter.c b/src/libecoPCR/ecofilter.c
new file mode 100644
index 0000000..d2a547f
--- /dev/null
+++ b/src/libecoPCR/ecofilter.c
@@ -0,0 +1,32 @@
+#include "ecoPCR.h"
+
+int eco_is_taxid_ignored(	int *ignored_taxid, 
+							int tab_len, 
+							int taxid)
+{
+	int i;
+	for (i=0; i < tab_len; i++){
+		if(taxid == ignored_taxid[i])
+			return 1;
+	}
+	return 0;
+}
+
+
+int eco_is_taxid_included(	ecotaxonomy_t *taxonomy, 
+							int *restricted_taxid, 
+							int32_t tab_len, 
+							int32_t taxid)
+{
+	int i;
+	ecotx_t *taxon;
+	
+	taxon = eco_findtaxonbytaxid(taxonomy, taxid);
+	
+	for (i=0; i < tab_len; i++)
+		if ( (taxon->taxid == restricted_taxid[i]) ||
+			 (eco_isundertaxon(taxon, restricted_taxid[i])) )
+			return 1;
+	
+	return 0;
+}
\ No newline at end of file