--- a/taskcluster/ci/build/kind.yml
+++ b/taskcluster/ci/build/kind.yml
@@ -13,8 +13,34 @@ transforms:
     - taskgraph.transforms.build_lints:transforms
     - taskgraph.transforms.use_toolchains:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms
 
 jobs-from:
     - linux.yml
     - macosx.yml
+
+job-defaults:
+    when:
+      files-changed:
+        # Include everything in comm-central except suite/ and im/
+        # https://bugzilla.mozilla.org/show_bug.cgi?id=1422060
+        - comm/build
+        - comm/calendar
+        - comm/chat
+        - comm/common
+        - comm/config
+        - comm/db
+        - comm/editor
+        - comm/ldap/
+        - comm/mail/
+        - comm/mailnews/
+        - comm/mozharness/
+        - comm/other-licenses/
+        - comm/python/
+        - comm/taskcluster/
+        - comm/testing/
+        - comm/.taskcluster.yml
+        - comm/AUTHORS
+        - comm/comm-confvars.sh
+        - comm/moz.build
+        - comm/moz.configure

--- a/taskcluster/ci/test/tests.yml
+++ b/taskcluster/ci/test/tests.yml
@@ -2,16 +2,41 @@
 # processed through the transformations described in kind.yml to produce a
 # bunch of tasks.  See the schema in `taskcluster/taskgraph/transforms/tests.py`
 # for a description of the fields used here.
 
 # Note that these are in lexical order, as enforced by the task loader.
 
 # Adding a new test type or running tests on a new platform? Be sure to review
 # https://wiki.mozilla.org/Sheriffing/Job_Visibility_Policy
+job-defaults:
+    when:
+      files-changed:
+        # Include everything in comm-central except suite/ and im/
+        # https://bugzilla.mozilla.org/show_bug.cgi?id=1422060
+        - comm/build
+        - comm/calendar
+        - comm/chat
+        - comm/common
+        - comm/config
+        - comm/db
+        - comm/editor
+        - comm/ldap/
+        - comm/mail/
+        - comm/mailnews/
+        - comm/mozharness/
+        - comm/other-licenses/
+        - comm/python/
+        - comm/taskcluster/
+        - comm/testing/
+        - comm/.taskcluster.yml
+        - comm/AUTHORS
+        - comm/comm-confvars.sh
+        - comm/moz.build
+        - comm/moz.configure
 
 xpcshell:
     description: "xpcshell test run"
     suite: xpcshell
     treeherder-symbol: tc-X(X)
     run-on-projects: built-projects
     docker-image:
         in-tree: "desktop1604-test"