diff --git a/test/built-ins/Temporal/Instant/from/instant-string-sub-minute-offset.js b/test/built-ins/Temporal/Instant/from/instant-string-sub-minute-offset.js
index 70c3f19870..9cafc51d55 100644
--- a/test/built-ins/Temporal/Instant/from/instant-string-sub-minute-offset.js
+++ b/test/built-ins/Temporal/Instant/from/instant-string-sub-minute-offset.js
@@ -10,3 +10,53 @@ features: [Temporal]
 const str = "1970-01-01T00:19:32.37+00:19:32.37";
 const result = Temporal.Instant.from(str);
 assert.sameValue(result.epochNanoseconds, 0n, "if present, sub-minute offset is accepted exactly");
+
+[
+  "2021-08-19T17:30-07:00:01[-07:00:01]",
+  "2021-08-19T17:30-07:00:00[-07:00:00]",
+  "2021-08-19T17:30-07:00:00.1[-07:00:00.1]",
+  "2021-08-19T17:30-07:00:00.0[-07:00:00.0]",
+  "2021-08-19T17:30-07:00:00.01[-07:00:00.01]",
+  "2021-08-19T17:30-07:00:00.00[-07:00:00.00]",
+  "2021-08-19T17:30-07:00:00.001[-07:00:00.001]",
+  "2021-08-19T17:30-07:00:00.000[-07:00:00.000]",
+  "2021-08-19T17:30-07:00:00.0001[-07:00:00.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-07:00:00.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-07:00:00.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-07:00:00.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-07:00:00.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-07:00:00.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-07:00:00.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-07:00:00.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-07:00:00.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-07:00:00.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-07:00:00.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-07:00:00.000000000]",
+
+  "2021-08-19T17:30-07:00:01[-070001]",
+  "2021-08-19T17:30-07:00:00[-070000]",
+  "2021-08-19T17:30-07:00:00.1[-070000.1]",
+  "2021-08-19T17:30-07:00:00.0[-070000.0]",
+  "2021-08-19T17:30-07:00:00.01[-070000.01]",
+  "2021-08-19T17:30-07:00:00.00[-070000.00]",
+  "2021-08-19T17:30-07:00:00.001[-070000.001]",
+  "2021-08-19T17:30-07:00:00.000[-070000.000]",
+  "2021-08-19T17:30-07:00:00.0001[-070000.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-070000.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-070000.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-070000.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-070000.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-070000.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-070000.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-070000.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-070000.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-070000.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-070000.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-070000.000000000]"
+].forEach((str) => {
+  assert.throws(
+    RangeError,
+    () => Temporal.Instant.from(str),
+    `ISO strings cannot have sub-minute offsets in time zone annotations: ${str}`
+  );
+});
diff --git a/test/built-ins/Temporal/Instant/prototype/equals/instant-string-sub-minute-offset.js b/test/built-ins/Temporal/Instant/prototype/equals/instant-string-sub-minute-offset.js
index 5bbaaf32c4..fc4d5c5d3e 100644
--- a/test/built-ins/Temporal/Instant/prototype/equals/instant-string-sub-minute-offset.js
+++ b/test/built-ins/Temporal/Instant/prototype/equals/instant-string-sub-minute-offset.js
@@ -12,3 +12,53 @@ const instance = new Temporal.Instant(0n);
 const str = "1970-01-01T00:19:32.37+00:19:32.37";
 const result = instance.equals(str);
 assert.sameValue(result, true, "if present, sub-minute offset is accepted exactly");
+
+[
+  "2021-08-19T17:30-07:00:01[-07:00:01]",
+  "2021-08-19T17:30-07:00:00[-07:00:00]",
+  "2021-08-19T17:30-07:00:00.1[-07:00:00.1]",
+  "2021-08-19T17:30-07:00:00.0[-07:00:00.0]",
+  "2021-08-19T17:30-07:00:00.01[-07:00:00.01]",
+  "2021-08-19T17:30-07:00:00.00[-07:00:00.00]",
+  "2021-08-19T17:30-07:00:00.001[-07:00:00.001]",
+  "2021-08-19T17:30-07:00:00.000[-07:00:00.000]",
+  "2021-08-19T17:30-07:00:00.0001[-07:00:00.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-07:00:00.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-07:00:00.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-07:00:00.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-07:00:00.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-07:00:00.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-07:00:00.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-07:00:00.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-07:00:00.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-07:00:00.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-07:00:00.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-07:00:00.000000000]",
+
+  "2021-08-19T17:30-07:00:01[-070001]",
+  "2021-08-19T17:30-07:00:00[-070000]",
+  "2021-08-19T17:30-07:00:00.1[-070000.1]",
+  "2021-08-19T17:30-07:00:00.0[-070000.0]",
+  "2021-08-19T17:30-07:00:00.01[-070000.01]",
+  "2021-08-19T17:30-07:00:00.00[-070000.00]",
+  "2021-08-19T17:30-07:00:00.001[-070000.001]",
+  "2021-08-19T17:30-07:00:00.000[-070000.000]",
+  "2021-08-19T17:30-07:00:00.0001[-070000.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-070000.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-070000.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-070000.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-070000.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-070000.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-070000.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-070000.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-070000.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-070000.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-070000.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-070000.000000000]"
+].forEach((str) => {
+  assert.throws(
+    RangeError,
+    () => instance.equals(str),
+    `ISO strings cannot have sub-minute offsets in time zone annotations: ${str}`
+  );
+});
diff --git a/test/built-ins/Temporal/Instant/prototype/since/instant-string-sub-minute-offset.js b/test/built-ins/Temporal/Instant/prototype/since/instant-string-sub-minute-offset.js
index 00e766024f..74168101a3 100644
--- a/test/built-ins/Temporal/Instant/prototype/since/instant-string-sub-minute-offset.js
+++ b/test/built-ins/Temporal/Instant/prototype/since/instant-string-sub-minute-offset.js
@@ -13,3 +13,53 @@ const instance = new Temporal.Instant(0n);
 const str = "1970-01-01T00:19:32.37+00:19:32.37";
 const result = instance.since(str);
 TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "if present, sub-minute offset is accepted exactly");
+
+[
+  "2021-08-19T17:30-07:00:01[-07:00:01]",
+  "2021-08-19T17:30-07:00:00[-07:00:00]",
+  "2021-08-19T17:30-07:00:00.1[-07:00:00.1]",
+  "2021-08-19T17:30-07:00:00.0[-07:00:00.0]",
+  "2021-08-19T17:30-07:00:00.01[-07:00:00.01]",
+  "2021-08-19T17:30-07:00:00.00[-07:00:00.00]",
+  "2021-08-19T17:30-07:00:00.001[-07:00:00.001]",
+  "2021-08-19T17:30-07:00:00.000[-07:00:00.000]",
+  "2021-08-19T17:30-07:00:00.0001[-07:00:00.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-07:00:00.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-07:00:00.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-07:00:00.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-07:00:00.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-07:00:00.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-07:00:00.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-07:00:00.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-07:00:00.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-07:00:00.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-07:00:00.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-07:00:00.000000000]",
+
+  "2021-08-19T17:30-07:00:01[-070001]",
+  "2021-08-19T17:30-07:00:00[-070000]",
+  "2021-08-19T17:30-07:00:00.1[-070000.1]",
+  "2021-08-19T17:30-07:00:00.0[-070000.0]",
+  "2021-08-19T17:30-07:00:00.01[-070000.01]",
+  "2021-08-19T17:30-07:00:00.00[-070000.00]",
+  "2021-08-19T17:30-07:00:00.001[-070000.001]",
+  "2021-08-19T17:30-07:00:00.000[-070000.000]",
+  "2021-08-19T17:30-07:00:00.0001[-070000.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-070000.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-070000.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-070000.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-070000.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-070000.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-070000.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-070000.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-070000.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-070000.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-070000.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-070000.000000000]"
+].forEach((str) => {
+  assert.throws(
+    RangeError,
+    () => instance.since(str),
+    `ISO strings cannot have sub-minute offsets in time zone annotations: ${str}`
+  );
+});
diff --git a/test/built-ins/Temporal/Instant/prototype/until/instant-string-sub-minute-offset.js b/test/built-ins/Temporal/Instant/prototype/until/instant-string-sub-minute-offset.js
index 9630b1a4f0..1d035e88c3 100644
--- a/test/built-ins/Temporal/Instant/prototype/until/instant-string-sub-minute-offset.js
+++ b/test/built-ins/Temporal/Instant/prototype/until/instant-string-sub-minute-offset.js
@@ -13,3 +13,53 @@ const instance = new Temporal.Instant(0n);
 const str = "1970-01-01T00:19:32.37+00:19:32.37";
 const result = instance.until(str);
 TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "if present, sub-minute offset is accepted exactly");
+
+[
+  "2021-08-19T17:30-07:00:01[-07:00:01]",
+  "2021-08-19T17:30-07:00:00[-07:00:00]",
+  "2021-08-19T17:30-07:00:00.1[-07:00:00.1]",
+  "2021-08-19T17:30-07:00:00.0[-07:00:00.0]",
+  "2021-08-19T17:30-07:00:00.01[-07:00:00.01]",
+  "2021-08-19T17:30-07:00:00.00[-07:00:00.00]",
+  "2021-08-19T17:30-07:00:00.001[-07:00:00.001]",
+  "2021-08-19T17:30-07:00:00.000[-07:00:00.000]",
+  "2021-08-19T17:30-07:00:00.0001[-07:00:00.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-07:00:00.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-07:00:00.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-07:00:00.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-07:00:00.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-07:00:00.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-07:00:00.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-07:00:00.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-07:00:00.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-07:00:00.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-07:00:00.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-07:00:00.000000000]",
+
+  "2021-08-19T17:30-07:00:01[-070001]",
+  "2021-08-19T17:30-07:00:00[-070000]",
+  "2021-08-19T17:30-07:00:00.1[-070000.1]",
+  "2021-08-19T17:30-07:00:00.0[-070000.0]",
+  "2021-08-19T17:30-07:00:00.01[-070000.01]",
+  "2021-08-19T17:30-07:00:00.00[-070000.00]",
+  "2021-08-19T17:30-07:00:00.001[-070000.001]",
+  "2021-08-19T17:30-07:00:00.000[-070000.000]",
+  "2021-08-19T17:30-07:00:00.0001[-070000.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-070000.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-070000.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-070000.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-070000.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-070000.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-070000.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-070000.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-070000.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-070000.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-070000.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-070000.000000000]"
+].forEach((str) => {
+  assert.throws(
+    RangeError,
+    () => instance.until(str),
+    `ISO strings cannot have sub-minute offsets in time zone annotations: ${str}`
+  );
+});
diff --git a/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/instant-string-sub-minute-offset.js b/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/instant-string-sub-minute-offset.js
index 766cec0863..be7af0b136 100644
--- a/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/instant-string-sub-minute-offset.js
+++ b/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/instant-string-sub-minute-offset.js
@@ -13,3 +13,53 @@ const instance = new Temporal.TimeZone("UTC");
 const str = "1970-01-01T00:19:32.37+00:19:32.37";
 const result = instance.getPlainDateTimeFor(str);
 TemporalHelpers.assertPlainDateTime(result, 1970, 1, "M01", 1, 0, 0, 0, 0, 0, 0, "if present, sub-minute offset is accepted exactly");
+
+[
+  "2021-08-19T17:30-07:00:01[-07:00:01]",
+  "2021-08-19T17:30-07:00:00[-07:00:00]",
+  "2021-08-19T17:30-07:00:00.1[-07:00:00.1]",
+  "2021-08-19T17:30-07:00:00.0[-07:00:00.0]",
+  "2021-08-19T17:30-07:00:00.01[-07:00:00.01]",
+  "2021-08-19T17:30-07:00:00.00[-07:00:00.00]",
+  "2021-08-19T17:30-07:00:00.001[-07:00:00.001]",
+  "2021-08-19T17:30-07:00:00.000[-07:00:00.000]",
+  "2021-08-19T17:30-07:00:00.0001[-07:00:00.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-07:00:00.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-07:00:00.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-07:00:00.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-07:00:00.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-07:00:00.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-07:00:00.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-07:00:00.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-07:00:00.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-07:00:00.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-07:00:00.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-07:00:00.000000000]",
+
+  "2021-08-19T17:30-07:00:01[-070001]",
+  "2021-08-19T17:30-07:00:00[-070000]",
+  "2021-08-19T17:30-07:00:00.1[-070000.1]",
+  "2021-08-19T17:30-07:00:00.0[-070000.0]",
+  "2021-08-19T17:30-07:00:00.01[-070000.01]",
+  "2021-08-19T17:30-07:00:00.00[-070000.00]",
+  "2021-08-19T17:30-07:00:00.001[-070000.001]",
+  "2021-08-19T17:30-07:00:00.000[-070000.000]",
+  "2021-08-19T17:30-07:00:00.0001[-070000.0001]",
+  "2021-08-19T17:30-07:00:00.0000[-070000.0000]",
+  "2021-08-19T17:30-07:00:00.00001[-070000.00001]",
+  "2021-08-19T17:30-07:00:00.00000[-070000.00000]",
+  "2021-08-19T17:30-07:00:00.000001[-070000.000001]",
+  "2021-08-19T17:30-07:00:00.000000[-070000.000000]",
+  "2021-08-19T17:30-07:00:00.0000001[-070000.0000001]",
+  "2021-08-19T17:30-07:00:00.0000000[-070000.0000000]",
+  "2021-08-19T17:30-07:00:00.00000001[-070000.00000001]",
+  "2021-08-19T17:30-07:00:00.00000000[-070000.00000000]",
+  "2021-08-19T17:30-07:00:00.000000001[-070000.000000001]",
+  "2021-08-19T17:30-07:00:00.000000000[-070000.000000000]"
+].forEach((str) => {
+  assert.throws(
+    RangeError,
+    () => instance.getPlainDateTimeFor(str),
+    `ISO strings cannot have sub-minute offsets in time zone annotations: ${str}`
+  );
+});
diff --git a/test/staging/Temporal/Regex/old/instant.js b/test/staging/Temporal/Regex/old/instant.js
index 218799e150..cfb8254728 100644
--- a/test/staging/Temporal/Regex/old/instant.js
+++ b/test/staging/Temporal/Regex/old/instant.js
@@ -32,10 +32,6 @@ function generateTest(dateTimeString, zoneString, components) {
   "+01:00",
   "+01",
   "+0100",
-  "+01:00:00",
-  "+010000",
-  "+01:00:00.000000000",
-  "+010000.0"
 ].forEach(zoneString => {
   generateTest("1976-11-18T15:23", `${ zoneString }[Europe/Vienna]`, [
     1976,