diff --git a/scroll-animations/css/timeline-offset-in-keyframe-change-timeline.tentative.html b/scroll-animations/css/timeline-offset-in-keyframe-change-timeline.tentative.html
index 6456e8aa779da7..5ac54081845605 100644
--- a/scroll-animations/css/timeline-offset-in-keyframe-change-timeline.tentative.html
+++ b/scroll-animations/css/timeline-offset-in-keyframe-change-timeline.tentative.html
@@ -76,7 +76,14 @@
       // Initially using a document timeline, so the keyframes should be
       // ignored.
       let frames = anim.effect.getKeyframes();
-      let expected = [];
+      let expected = [
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
       assert_frame_lists_equal(frames, expected);
 
       // Once a view-timeline is added, the kefyrames must update to reflect
@@ -88,13 +95,15 @@
 
       frames = anim.effect.getKeyframes();
       expected = [
-        { offset: -1, computedOffset: -1, easing: "linear", composite: "auto",
-          marginLeft: "0px", opacity: "0" },
         { offset:  0, computedOffset: 0, easing: "linear", composite: "replace",
           marginRight: "10px" },
         { offset: 1, computedOffset: 1, easing: "linear", composite: "replace",
           marginLeft: "10px" },
-        { offset: 2, computedOffset: 2, easing: "linear", composite: "auto",
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 2, easing: "linear", composite: "auto",
           marginRight: "0px", opacity: "1" },
       ];
       assert_frame_lists_equal(frames, expected);
@@ -105,13 +114,15 @@
       await waitForNextFrame();
       frames = anim.effect.getKeyframes();
       expected = [
-        { offset: -1/3, computedOffset: -1/3, easing: "linear",
-          composite: "auto", marginLeft: "0px", opacity: "0" },
         { offset:  0, computedOffset: 0, easing: "linear", composite: "replace",
           marginRight: "10px" },
         { offset: 1, computedOffset: 1, easing: "linear", composite: "replace",
           marginLeft: "10px" },
-        { offset: 4/3, computedOffset: 4/3, easing: "linear", composite: "auto",
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1/3, easing: "linear",
+          composite: "auto", marginLeft: "0px", opacity: "0" },
+        { offset:  { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 4/3, easing: "linear", composite: "auto",
           marginRight: "0px", opacity: "1" },
       ];
       assert_frame_lists_equal(frames, expected);
@@ -120,9 +131,15 @@
       assert_equals(getComputedStyle(target).animationTimeline, 'auto',
                     'Switch back to document timeline');
       frames = anim.effect.getKeyframes();
-      expected = [];
+      expected = [
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
       assert_frame_lists_equal(frames, expected);
-
     }, 'getKeyframes with timeline-offsets');
   }
 
diff --git a/scroll-animations/css/timeline-offset-keyframes-hidden-subject.html b/scroll-animations/css/timeline-offset-keyframes-hidden-subject.html
index d3b124ba18e39d..047acfed33f36a 100644
--- a/scroll-animations/css/timeline-offset-keyframes-hidden-subject.html
+++ b/scroll-animations/css/timeline-offset-keyframes-hidden-subject.html
@@ -68,15 +68,17 @@
 
       let frames = anim.effect.getKeyframes();
       let expected_resolved_offsets = [
-        { offset: -1/3, computedOffset: -1/3, easing: "linear",
-          composite: "auto", marginLeft: "0px" },
         { offset:  0, computedOffset: 0, easing: "linear", composite: "replace",
           marginRight: "10px", opacity: "1" },
         { offset: 1/2, computedOffset: 1/2, easing: "linear",
           composite: "auto", opacity: "0.5" },
         { offset: 1, computedOffset: 1, easing: "linear", composite: "replace",
           marginLeft: "10px", opacity: "1" },
-        { offset: 4/3, computedOffset: 4/3, easing: "linear", composite: "auto",
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1/3, easing: "linear",
+          composite: "auto", marginLeft: "0px" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 4/3, easing: "linear", composite: "auto",
           marginRight: "0px" },
       ];
       assert_frame_lists_equal(frames, expected_resolved_offsets,
@@ -92,7 +94,13 @@
         { offset: 0.5, computedOffset: 0.5, opacity: "0.5", easing: "linear",
           composite: "auto", },
         { offset: 1, computedOffset: 1, opacity: "1", easing: "linear",
-          composite: "replace" }
+          composite: "replace" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: null, easing: "linear",
+          composite: "auto", marginLeft: "0px" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginRight: "0px" }
       ];
       assert_frame_lists_equal(frames, expected_unresolved_offsets,
                                'Keyframes with invalid view timeline');
diff --git a/scroll-animations/css/timeline-offset-keyframes-with-document-timeline.html b/scroll-animations/css/timeline-offset-keyframes-with-document-timeline.html
index 95a0ea4eae0cbf..03ee381fd9276f 100644
--- a/scroll-animations/css/timeline-offset-keyframes-with-document-timeline.html
+++ b/scroll-animations/css/timeline-offset-keyframes-with-document-timeline.html
@@ -12,15 +12,15 @@
 </head>
 <style type="text/css">
   @keyframes anim {
+    cover 100% {
+      margin-right: 0px;
+    }
     cover 0% {
       margin-left:  0px;
     }
     50% {
       opacity:  0.5;
     }
-    cover 100% {
-      margin-right: 0px;
-    }
   }
   #scroller {
     border:  10px solid lightgray;
@@ -61,13 +61,19 @@
         { offset: 0, computedOffset: 0, opacity: "1", easing: "linear",
           composite: "replace" },
         { offset: 0.5, computedOffset: 0.5, opacity: "0.5", easing: "linear",
-          composite: "auto", },
+          composite: "auto" },
         { offset: 1, computedOffset: 1, opacity: "1", easing: "linear",
-          composite: "replace" }
+          composite: "replace" },
+        { offset: { rangeName: "cover", offset: CSS.percent(100) },
+          computedOffset: null, marginRight:  "0px", composite: "auto",
+          easing: "linear" },
+        { offset: { rangeName: "cover", offset: CSS.percent(0) },
+          computedOffset: null, marginLeft:  "0px", composite: "auto",
+          easing: "linear" }
       ];
       assert_frame_lists_equal(frames, expected);
-    }, 'Keyframes with timeline-offsets ignored when using document ' +
-       'timeline');
+    }, 'Keyframes with timeline-offsets reported but not reachable when ' +
+       'using a document timeline');
   }
 
   window.onload = runTest;
diff --git a/scroll-animations/view-timelines/get-keyframes-with-timeline-offset.html b/scroll-animations/view-timelines/get-keyframes-with-timeline-offset.html
new file mode 100644
index 00000000000000..02f910d04e3316
--- /dev/null
+++ b/scroll-animations/view-timelines/get-keyframes-with-timeline-offset.html
@@ -0,0 +1,203 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<!-- TODO(kevers): Insert link once resolutions present in spec -->
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/web-animations/testcommon.js"></script>
+<script src="/web-animations/resources/keyframe-utils.js"></script>
+<script src="support/testcommon.js"></script>
+<title>Reported keyframes containing timeline offset</title>
+</head>
+<style type="text/css">
+  #scroller {
+    border:  10px solid lightgray;
+    overflow-y: scroll;
+    overflow-x: hidden;
+    width: 300px;
+    height: 200px;
+  }
+  #target {
+    margin: 800px 10px;
+    width: 100px;
+    height: 100px;
+    z-index: -1;
+    background-color: green;
+  }
+</style>
+<body>
+  <div id=scroller>
+    <div id=target></div>
+  </div>
+</body>
+<script type="text/javascript">
+  async function runTest() {
+    function createAnimation(t, keyframes, use_view_timeline = true) {
+      const options = {
+        rangeStart: { rangeName: 'contain', offset: CSS.percent(0) },
+        rangeEnd: { rangeName: 'contain', offset: CSS.percent(100) },
+        duration: 'auto',
+        fill: 'both'
+      };
+      if (use_view_timeline) {
+        options.timeline = new ViewTimeline( { subject: target });
+      }
+      const anim = target.animate(keyframes, options);
+      t.add_cleanup(() => {
+        anim.cancel();
+      });
+      return anim;
+    }
+
+    promise_test(async t => {
+      let anim = createAnimation(t, [
+        { offset: "contain 25%", marginLeft: "0px", opacity: "0" },
+        { offset: "contain 75%", marginRight: "0px", opacity: "1" }
+      ]);
+      let frames = anim.effect.getKeyframes();
+      let expected = [
+        { offset: { rangeName: 'contain', offset: CSS.percent(25) },
+          computedOffset: 0.25, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'contain', offset: CSS.percent(75) },
+          computedOffset: 0.75, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+    }, 'Report specified timeline offsets');
+
+    promise_test(async t => {
+      let anim = createAnimation(t, [
+        { offset: "cover 0%", marginLeft: "0px", opacity: "0" },
+        { offset: "cover 100%", marginRight: "0px", opacity: "1" }
+      ]);
+      let frames = anim.effect.getKeyframes();
+      let expected = [
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 2, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+    }, 'Computed offsets can be outside [0,1] for keyframes with timeline ' +
+       'offsets');
+
+    promise_test(async t => {
+      let anim = createAnimation(t, [
+        { offset: "contain 75%", marginLeft: "0px", opacity: "0" },
+        { offset: "contain 25%", marginRight: "0px", opacity: "1" }
+      ]);
+      let frames = anim.effect.getKeyframes();
+      let expected = [
+        { offset: { rangeName: 'contain', offset: CSS.percent(75) },
+          computedOffset: 0.75, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'contain', offset: CSS.percent(25) },
+          computedOffset: 0.25, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+    }, 'Retain specified ordering of keyframes with timeline offsets');
+
+    promise_test(async t => {
+      let anim = createAnimation(t, [
+        { offset: "cover 0%", marginLeft: "0px", opacity: "0" },
+        { offset: "cover 100%", marginRight: "0px", opacity: "1" }
+      ], /* use_view_timeline */ false);
+      let frames = anim.effect.getKeyframes();
+      let expected = [
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: null, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+    }, 'Include unreachable keyframes');
+
+
+    promise_test(async t => {
+      let anim = createAnimation(t, [
+        { offset: "cover 0%", marginLeft: "0px", opacity: 0 },
+        { offset: "cover 100%", marginRight: "0px", opacity: 1 },
+        { opacity: 0 },
+        { opacity: 0.5 },
+        { opacity: 1.0 }
+      ]);
+      let frames = anim.effect.getKeyframes();
+      let expected = [
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 2, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" },
+        { offset: null, computedOffset: 0, easing: "linear", composite: "auto",
+          opacity: "0" },
+        { offset: null, computedOffset: 0.5, easing: "linear",
+          composite: "auto", opacity: "0.5" },
+        { offset: null, computedOffset: 1.0, easing: "linear",
+          composite: "auto", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+
+      anim = createAnimation(t, [
+        { opacity: 0 },
+        { offset: "cover 0%", marginLeft: "0px", opacity: 0 },
+        { opacity: 0.5 },
+        { offset: "cover 100%", marginRight: "0px", opacity: 1 },
+        { opacity: 1.0 }
+      ]);
+      frames = anim.effect.getKeyframes();
+      expected = [
+        { offset: null, computedOffset: 0, easing: "linear", composite: "auto",
+          opacity: "0" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: null, computedOffset: 0.5, easing: "linear",
+          composite: "auto", opacity: "0.5" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 2, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" },
+        { offset: null, computedOffset: 1.0, easing: "linear",
+          composite: "auto", opacity: "1" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+
+      anim = createAnimation(t, [
+        { opacity: 0.2, offset: 0.2 },
+        { offset: "cover 0%", marginLeft: "0px", opacity: 0 },
+        { opacity: 0.4 },
+        { opacity: 0.6 },
+        { offset: "cover 100%", marginRight: "0px", opacity: 1 },
+        { opacity: 0.8, offset: 0.8 }
+      ]);
+      frames = anim.effect.getKeyframes();
+      expected = [
+        { offset: 0.2, computedOffset: 0.2, easing: "linear", composite: "auto",
+          opacity: "0.2" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(0) },
+          computedOffset: -1, easing: "linear", composite: "auto",
+          marginLeft: "0px", opacity: "0" },
+        { offset: null, computedOffset: 0.4, easing: "linear",
+          composite: "auto", opacity: "0.4" },
+        { offset: null, computedOffset: 0.6, easing: "linear",
+          composite: "auto", opacity: "0.6" },
+        { offset: { rangeName: 'cover', offset: CSS.percent(100) },
+          computedOffset: 2, easing: "linear", composite: "auto",
+          marginRight: "0px", opacity: "1" },
+        { offset: 0.8, computedOffset: 0.8, easing: "linear", composite: "auto",
+          opacity: "0.8" }
+      ];
+      assert_frame_lists_equal(frames, expected);
+    }, 'Mix of computed and timeline offsets.');
+  }
+
+  window.onload = runTest;
+</script>
+</html>
diff --git a/web-animations/resources/keyframe-utils.js b/web-animations/resources/keyframe-utils.js
index 8e6e5840f7f872..60fb9781a0c080 100644
--- a/web-animations/resources/keyframe-utils.js
+++ b/web-animations/resources/keyframe-utils.js
@@ -31,8 +31,20 @@ function assert_frames_equal(a, b, name) {
                 `properties on ${name} should match`);
   // Iterates sorted keys to ensure stable failures.
   for (const p of Object.keys(a).sort()) {
-    if (typeof a[p] == 'number')
+    if (typeof b[p] == 'number')
       assert_approx_equals(a[p], b[p], 1e-6, `value for '${p}' on ${name}`);
+    else if (typeof b[p] == 'object') {
+      for (const key in b[p]) {
+        if (typeof b[p][key] == 'number') {
+          assert_approx_equals(a[p][key], b[p][key], 1e-6,
+                               `value for '${p}.${key}' on ${name}`);
+        } else {
+          assert_equals((a[p][key] || 'undefined').toString(),
+                         b[p][key].toString(),
+                        `value for '${p}.${key}' on ${name}`);
+        }
+      }
+    }
     else
       assert_equals(a[p], b[p], `value for '${p}' on ${name}`);
   }