diff --git a/accounts/config/config-tags.ledger b/accounts/config/config-tags.ledger
index f017131d59f3cd3a83234051d42052f027fe46d2..3d7ad21e3e5cfe30d1b99eb841ee7d45ccd2a4c7 100644
--- a/accounts/config/config-tags.ledger
+++ b/accounts/config/config-tags.ledger
@@ -47,3 +47,10 @@ tag IncomeType
 tag Program
     assert value =~ /[ A-z0-9\-]+(:[ A-z0-9\-]+)*/
     check  value =~ /^(Main Org:(Overhead|Direct Fundraising))$/
+
+
+; Entity tag is just a string, but shouldn't have spaces, just letters,
+; numbers and dashes.
+
+tag Entity
+    assert value =~ /[ A-z0-9\-]+(:[ A-z0-9\-]+)*/