diff --git a/internal/base/server/http_funcmap.go b/internal/base/server/http_funcmap.go
index a5d530b50..cf3cf5144 100644
--- a/internal/base/server/http_funcmap.go
+++ b/internal/base/server/http_funcmap.go
@@ -78,8 +78,7 @@ var funcMap = template.FuncMap{
 		return trans
 	},
 	"timeFormatISO": func(tz string, timestamp int64) string {
-		_, _ = time.LoadLocation(tz)
-		return time.Unix(timestamp, 0).Format("2006-01-02T15:04:05.000Z")
+		return day.FormatISO(timestamp, tz)
 	},
 	"translatorTimeFormatLongDate": func(la i18n.Language, tz string, timestamp int64) string {
 		trans := translator.GlobalTrans.Tr(la, "ui.dates.long_date_with_time")
@@ -91,7 +90,6 @@ var funcMap = template.FuncMap{
 			between int64 = 0
 			trans   string
 		)
-		_, _ = time.LoadLocation(tz)
 		if now > timestamp {
 			between = now - timestamp
 		}
@@ -119,7 +117,7 @@ var funcMap = template.FuncMap{
 
 		if between >= 3600*24 &&
 			between < 3600*24*366 &&
-			time.Unix(timestamp, 0).Format("2006") == time.Unix(now, 0).Format("2006") {
+			sameYearInZone(timestamp, now, tz) {
 			trans = translator.GlobalTrans.Tr(la, "ui.dates.long_date")
 			return day.Format(timestamp, trans, tz)
 		}
@@ -137,6 +135,18 @@ var funcMap = template.FuncMap{
 	"urlTitle": htmltext.UrlTitle,
 }
 
+// sameYearInZone reports whether two instants fall into the same calendar
+// year when rendered in the given IANA zone. The relative/absolute date
+// rendering uses this to decide whether the year may be omitted, and the
+// decision must follow the zone the value is rendered in, not the server's
+// zone: two instants sharing a year in Tokyo can sit on opposite sides of
+// New Year in Los Angeles.
+func sameYearInZone(a, b int64, tz string) bool {
+	yearA := time.Unix(a, 0).In(day.Location(tz)).Format("2006")
+	yearB := time.Unix(b, 0).In(day.Location(tz)).Format("2006")
+	return yearA == yearB
+}
+
 func FormatLinkNofollow(html string) string {
 	var hrefRegexp = regexp.MustCompile("(?m)<a.*?[^<]>.*?</a>")
 	match := hrefRegexp.FindAllString(html, -1)
diff --git a/internal/base/server/http_funcmap_test.go b/internal/base/server/http_funcmap_test.go
new file mode 100644
index 000000000..cb0aba5df
--- /dev/null
+++ b/internal/base/server/http_funcmap_test.go
@@ -0,0 +1,80 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package server
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// timeFormatISO feeds every server-rendered <time datetime="..."> attribute:
+// it must render the instant in the requested zone with a real ISO-8601 zone
+// marker ("Z" only for UTC), not the server's local wall clock labeled as Z.
+func TestTimeFormatISO(t *testing.T) {
+	// 2023-11-14 22:13:20 UTC
+	const ts = int64(1700000000)
+	formatISO := funcMap["timeFormatISO"].(func(string, int64) string)
+
+	tests := []struct {
+		name     string
+		tz       string
+		expected string
+	}{
+		{"utc_renders_z", "UTC", "2023-11-14T22:13:20.000Z"},
+		{"tokyo_offset", "Asia/Tokyo", "2023-11-15T07:13:20.000+09:00"},
+		{"new_york_offset", "America/New_York", "2023-11-14T17:13:20.000-05:00"},
+		{"kolkata_half_hour", "Asia/Kolkata", "2023-11-15T03:43:20.000+05:30"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, formatISO(tt.tz, ts))
+		})
+	}
+}
+
+// An empty or unknown zone must fall back to the server's local zone rendered
+// with a real marker, matching the semantics day.Format established.
+func TestTimeFormatISOFallsBackToLocalForUnknownZone(t *testing.T) {
+	const ts = int64(1700000000)
+	formatISO := funcMap["timeFormatISO"].(func(string, int64) string)
+	expected := time.Unix(ts, 0).In(time.Local).Format("2006-01-02T15:04:05.000Z07:00")
+
+	for _, tz := range []string{"", "Not/AZone", "UTC+99"} {
+		t.Run("tz="+tz, func(t *testing.T) {
+			assert.Equal(t, expected, formatISO(tz, ts))
+		})
+	}
+}
+
+// The long-date/short-date choice depends on the calendar year of the
+// rendered zone: two instants that share a year in Tokyo can sit on opposite
+// sides of New Year in Los Angeles.
+func TestSameYearInZone(t *testing.T) {
+	// 2024-01-01 08:00 JST == 2023-12-31 15:00 PST
+	const jstNewYear = int64(1704067200)
+	// 2024-06-01 08:00 JST == 2024-05-31 23:00 UTC
+	const midYear = int64(1717200000)
+
+	assert.True(t, sameYearInZone(midYear, jstNewYear, "Asia/Tokyo"))
+	assert.False(t, sameYearInZone(midYear, jstNewYear, "America/Los_Angeles"))
+}
diff --git a/internal/controller/template_controller.go b/internal/controller/template_controller.go
index 0f2f5b68b..2fb4677ce 100644
--- a/internal/controller/template_controller.go
+++ b/internal/controller/template_controller.go
@@ -45,6 +45,7 @@ import (
 	"github.com/apache/answer/internal/service/siteinfo_common"
 	"github.com/apache/answer/pkg/checker"
 	"github.com/apache/answer/pkg/converter"
+	"github.com/apache/answer/pkg/day"
 	"github.com/apache/answer/pkg/htmltext"
 	"github.com/apache/answer/pkg/obj"
 	"github.com/apache/answer/pkg/uid"
@@ -422,6 +423,9 @@ func (tc *TemplateController) QuestionInfo(ctx *gin.Context) {
 	if siteInfo.SiteSeo.Permalink == constant.PermalinkQuestionID || siteInfo.SiteSeo.Permalink == constant.PermalinkQuestionIDByShortID {
 		siteInfo.Canonical = fmt.Sprintf("%s/questions/%s", siteInfo.General.SiteUrl, id)
 	}
+	// JSON-LD dates are machine-read (search engines), so they must carry the
+	// site's configured zone like every other server-rendered date.
+	siteLoc := day.Location(siteInfo.Interface.TimeZone)
 	jsonLD := &schema.QAPageJsonLD{}
 	jsonLD.Context = "https://schema.org"
 	jsonLD.Type = "QAPage"
@@ -430,7 +434,7 @@ func (tc *TemplateController) QuestionInfo(ctx *gin.Context) {
 	jsonLD.MainEntity.Text = detail.HTML
 	jsonLD.MainEntity.AnswerCount = int(answerCount)
 	jsonLD.MainEntity.UpvoteCount = detail.VoteCount
-	jsonLD.MainEntity.DateCreated = time.Unix(detail.CreateTime, 0)
+	jsonLD.MainEntity.DateCreated = time.Unix(detail.CreateTime, 0).In(siteLoc)
 	jsonLD.MainEntity.Author.Type = "Person"
 	jsonLD.MainEntity.Author.Name = detail.UserInfo.DisplayName
 	jsonLD.MainEntity.Author.URL = fmt.Sprintf("%s/users/%s", siteInfo.General.SiteUrl, detail.UserInfo.Username)
@@ -440,7 +444,7 @@ func (tc *TemplateController) QuestionInfo(ctx *gin.Context) {
 			acceptedAnswerItem := &schema.AcceptedAnswerItem{}
 			acceptedAnswerItem.Type = "Answer"
 			acceptedAnswerItem.Text = answer.HTML
-			acceptedAnswerItem.DateCreated = time.Unix(answer.CreateTime, 0)
+			acceptedAnswerItem.DateCreated = time.Unix(answer.CreateTime, 0).In(siteLoc)
 			acceptedAnswerItem.UpvoteCount = answer.VoteCount
 			acceptedAnswerItem.URL = fmt.Sprintf("%s/%s", siteInfo.Canonical, answer.ID)
 			acceptedAnswerItem.Author.Type = "Person"
@@ -451,7 +455,7 @@ func (tc *TemplateController) QuestionInfo(ctx *gin.Context) {
 			item := &schema.SuggestedAnswerItem{}
 			item.Type = "Answer"
 			item.Text = answer.HTML
-			item.DateCreated = time.Unix(answer.CreateTime, 0)
+			item.DateCreated = time.Unix(answer.CreateTime, 0).In(siteLoc)
 			item.UpvoteCount = answer.VoteCount
 			item.URL = fmt.Sprintf("%s/%s", siteInfo.Canonical, answer.ID)
 			item.Author.Type = "Person"
diff --git a/pkg/day/day.go b/pkg/day/day.go
index 6c1cb498d..285ddc8d8 100644
--- a/pkg/day/day.go
+++ b/pkg/day/day.go
@@ -59,14 +59,27 @@ func Format(unix int64, format, tz string) (formatted string) {
 		from = suffix
 	}
 
+	formatted = time.Unix(unix, 0).In(Location(tz)).Format(toFormat.String())
+	return
+}
+
+// Location resolves an IANA time zone name to a *time.Location. An empty or
+// unknown name falls back to the server's local zone, so a bad configuration
+// never shifts the instant that is being rendered.
+func Location(tz string) *time.Location {
 	loc, err := time.LoadLocation(tz)
 	if err != nil || tz == "" {
-		// An empty or unknown zone must not shift the instant that is being
-		// rendered: fall back to the server local zone.
-		loc = time.Local
+		return time.Local
 	}
-	formatted = time.Unix(unix, 0).In(loc).Format(toFormat.String())
-	return
+	return loc
+}
+
+// FormatISO renders a unix timestamp as an ISO-8601 string in the given IANA
+// time zone, e.g. "2023-11-15T07:13:20.000+09:00". The zone marker is a real
+// offset, or "Z" when the instant renders in UTC, so the output is always a
+// valid datetime attribute for the <time> element and for schema.org dates.
+func FormatISO(unix int64, tz string) string {
+	return time.Unix(unix, 0).In(Location(tz)).Format("2006-01-02T15:04:05.000Z07:00")
 }
 
 func nextStdChunk(from []rune) (to, suffix []rune) {
diff --git a/pkg/day/day_test.go b/pkg/day/day_test.go
index 3dd0f37d1..c47de6181 100644
--- a/pkg/day/day_test.go
+++ b/pkg/day/day_test.go
@@ -143,3 +143,42 @@ func TestFormatUnknownTimezoneFallsBackToLocal(t *testing.T) {
 		})
 	}
 }
+
+// Location resolves an IANA name and must fall back to the server's local
+// zone for empty or unknown names, so a bad configuration never shifts the
+// rendered instant.
+func TestLocation(t *testing.T) {
+	assert.Equal(t, time.UTC, Location("UTC"))
+	assert.Equal(t, time.Local, Location(""))
+	assert.Equal(t, time.Local, Location("Not/AZone"))
+
+	tokyo, err := time.LoadLocation("Asia/Tokyo")
+	assert.Nil(t, err)
+	assert.Equal(t, tokyo, Location("Asia/Tokyo"))
+}
+
+// FormatISO feeds every server-rendered <time datetime="..."> attribute: it
+// renders the instant in the requested zone with a real ISO-8601 marker -
+// "Z" only for UTC, an explicit offset otherwise.
+func TestFormatISO(t *testing.T) {
+	// 2023-11-14 22:13:20 UTC
+	const sec = int64(1700000000)
+
+	tests := []struct {
+		name     string
+		tz       string
+		expected string
+	}{
+		{"utc_renders_z", "UTC", "2023-11-14T22:13:20.000Z"},
+		{"tokyo_offset", "Asia/Tokyo", "2023-11-15T07:13:20.000+09:00"},
+		{"new_york_offset", "America/New_York", "2023-11-14T17:13:20.000-05:00"},
+		{"kolkata_half_hour", "Asia/Kolkata", "2023-11-15T03:43:20.000+05:30"},
+		{"london_winter_is_z", "Europe/London", "2023-11-14T22:13:20.000Z"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, FormatISO(sec, tt.tz))
+		})
+	}
+}