diff --git a/i18nlangtag/source/isolang/isolang.cxx b/i18nlangtag/source/isolang/isolang.cxx
index 629a85b48ace..3c61b435b394 100644
--- a/i18nlangtag/source/isolang/isolang.cxx
+++ b/i18nlangtag/source/isolang/isolang.cxx
@@ -686,6 +686,7 @@ IsoLanguageCountryEntry const aImplIsoLangEntries[] =
     { LANGUAGE_USER_ABKHAZ,                 "ab", ""  , k0    },
     { LANGUAGE_USER_ENGLISH_GUYANA,         "en", "GY", k0    },
     { LANGUAGE_USER_GRONINGS,              "gos", "NL", k0    },
+    { LANGUAGE_USER_EXTREMADURAN,          "ext", "ES", k0    },
     // Add new languages ^^^ there.
     { LANGUAGE_MULTIPLE,                   "mul", ""  , k0    },    // multiple languages, many languages are used
     { LANGUAGE_UNDETERMINED,               "und", ""  , k0    },    // undetermined language, language cannot be identified
diff --git a/i18npool/Library_localedata_es.mk b/i18npool/Library_localedata_es.mk
index 136368fa16da..1b4765b103bc 100644
--- a/i18npool/Library_localedata_es.mk
+++ b/i18npool/Library_localedata_es.mk
@@ -36,6 +36,7 @@ $(eval $(call gb_Library_add_generated_exception_objects,localedata_es,\
 	CustomTarget/i18npool/localedata/localedata_es_SV \
 	CustomTarget/i18npool/localedata/localedata_es_UY \
 	CustomTarget/i18npool/localedata/localedata_es_VE \
+	CustomTarget/i18npool/localedata/localedata_ext_ES \
 	CustomTarget/i18npool/localedata/localedata_gl_ES \
 	CustomTarget/i18npool/localedata/localedata_oc_ES_aranes \
 ))
diff --git a/i18npool/source/localedata/data/ext_ES.xml b/i18npool/source/localedata/data/ext_ES.xml
new file mode 100644
index 000000000000..b9cfa2e0d3bb
--- /dev/null
+++ b/i18npool/source/localedata/data/ext_ES.xml
@@ -0,0 +1,379 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE Locale SYSTEM 'locale.dtd'>
+<!--
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   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 .
+ -->
+<Locale versionDTD="2.0.3" allowUpdateFromCLDR="no" version="1.2">
+  <LC_INFO>
+    <Language>
+      <LangID>ext</LangID>
+      <DefaultName>Extremaduran</DefaultName>
+    </Language>
+    <Country>
+      <CountryID>ES</CountryID>
+      <DefaultName>Spain</DefaultName>
+    </Country>
+  </LC_INFO>
+  <LC_CTYPE>
+    <Separators>
+      <DateSeparator>/</DateSeparator>
+      <ThousandSeparator>.</ThousandSeparator>
+      <DecimalSeparator>,</DecimalSeparator>
+      <TimeSeparator>:</TimeSeparator>
+      <Time100SecSeparator>,</Time100SecSeparator>
+      <ListSeparator>;</ListSeparator>
+      <LongDateDayOfWeekSeparator>, </LongDateDayOfWeekSeparator>
+      <LongDateDaySeparator> de </LongDateDaySeparator>
+      <LongDateMonthSeparator> de </LongDateMonthSeparator>
+      <LongDateYearSeparator> </LongDateYearSeparator>
+    </Separators>
+    <Markers>
+      <QuotationStart>‘</QuotationStart>
+      <QuotationEnd>’</QuotationEnd>
+      <DoubleQuotationStart>“</DoubleQuotationStart>
+      <DoubleQuotationEnd>”</DoubleQuotationEnd>
+    </Markers>
+    <TimeAM>a. m.</TimeAM>
+    <TimePM>p. m.</TimePM>
+    <MeasurementSystem>metric</MeasurementSystem>
+  </LC_CTYPE>
+  <LC_FORMAT replaceFrom="[CURRENCY]" replaceTo="[$€-6B6]">
+    <DateAcceptancePattern>D/M</DateAcceptancePattern>
+    <FormatElement msgid="FixedFormatskey1" default="true" type="medium" usage="FIXED_NUMBER" formatindex="0">
+      <FormatCode>Estandar</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey2" default="true" type="short" usage="FIXED_NUMBER" formatindex="1">
+      <FormatCode>0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey3" default="false" type="medium" usage="FIXED_NUMBER" formatindex="2">
+      <FormatCode>0,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey4" default="false" type="short" usage="FIXED_NUMBER" formatindex="3">
+      <FormatCode>#.##0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey5" default="false" type="medium" usage="FIXED_NUMBER" formatindex="4">
+      <FormatCode>#.##0,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey6" default="false" type="medium" usage="FIXED_NUMBER" formatindex="5">
+      <FormatCode>#.###,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey9" default="false" type="medium" usage="FIXED_NUMBER" formatindex="101">
+      <FormatCode>[NatNum12 cardinal]0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey10" default="false" type="medium" usage="FIXED_NUMBER" formatindex="102">
+      <FormatCode>[NatNum12 capitalize cardinal]0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="FixedFormatskey12" default="false" type="medium" usage="FIXED_NUMBER" formatindex="104">
+      <FormatCode>[NatNum12 upper cardinal]0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="ScientificFormatskey1" default="false" type="medium" usage="SCIENTIFIC_NUMBER" formatindex="6">
+      <FormatCode>0,00E+000</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="ScientificFormatskey2" default="true" type="medium" usage="SCIENTIFIC_NUMBER" formatindex="7">
+      <FormatCode>0,00E+00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="ScientificFormatskey3" default="false" type="medium" usage="SCIENTIFIC_NUMBER" formatindex="78">
+      <FormatCode>##0,00E+00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="PercentFormatskey1" default="true" type="short" usage="PERCENT_NUMBER" formatindex="8">
+      <FormatCode>0" "%</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="PercentFormatskey2" default="true" type="long" usage="PERCENT_NUMBER" formatindex="9">
+      <FormatCode>0,00" "%</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey1" default="true" type="short" usage="CURRENCY" formatindex="12">
+      <FormatCode>#.##0 [CURRENCY];-#.##0 [CURRENCY]</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey2" default="false" type="medium" usage="CURRENCY" formatindex="13">
+      <FormatCode>#.##0 [CURRENCY];-#.##0 [CURRENCY]</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey3" default="true" type="medium" usage="CURRENCY" formatindex="14">
+      <FormatCode>#.##0 [CURRENCY];[RED]-#.##0 [CURRENCY]</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey4" default="false" type="medium" usage="CURRENCY" formatindex="15">
+      <FormatCode>#.##0 [CURRENCY];[RED]-#.##0 [CURRENCY]</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey5" default="false" type="medium" usage="CURRENCY" formatindex="16">
+      <FormatCode>#.##0 CCC</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey6" default="false" type="medium" usage="CURRENCY" formatindex="17">
+      <FormatCode>#.##0 [CURRENCY];[RED]-#.##0 [CURRENCY]</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey9" default="false" type="medium" usage="CURRENCY" formatindex="105">
+      <FormatCode>[NatNum12 CURRENCY]0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey10" default="false" type="medium" usage="CURRENCY" formatindex="106">
+      <FormatCode>[NatNum12 CURRENCY]0,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey11" default="false" type="medium" usage="CURRENCY" formatindex="107">
+      <FormatCode>[NatNum12 upper CURRENCY]0</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="CurrencyFormatskey12" default="false" type="medium" usage="CURRENCY" formatindex="108">
+      <FormatCode>[NatNum12 upper CURRENCY]0,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey1" default="true" type="short" usage="DATE" formatindex="18">
+      <FormatCode>D/MM/YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey9" default="true" type="long" usage="DATE" formatindex="19">
+      <FormatCode>NNNND "de" MMMM "de" YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey8" default="true" type="medium" usage="DATE" formatindex="20">
+      <FormatCode>DD/MM/YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey7" default="false" type="medium" usage="DATE" formatindex="21">
+      <FormatCode>DD/MM/YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey10" default="false" type="long" usage="DATE" formatindex="22">
+      <FormatCode>D "de" MMM "de" YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey11" default="false" type="long" usage="DATE" formatindex="23">
+      <FormatCode>D "de" MMM "de" YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey16" default="false" type="long" usage="DATE" formatindex="24">
+      <FormatCode>D. MMM. YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey12" default="false" type="long" usage="DATE" formatindex="25">
+      <FormatCode>D "de" MMMM "de" YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey17" default="false" type="long" usage="DATE" formatindex="26">
+      <FormatCode>D. MMMM YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey13" default="false" type="long" usage="DATE" formatindex="27">
+      <FormatCode>NN D "de" MMM "de" YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey2" default="false" type="medium" usage="DATE" formatindex="28">
+      <FormatCode>NN DD/MMM YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey14" default="false" type="long" usage="DATE" formatindex="29">
+      <FormatCode>NN D "de" MMMM "de" YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey15" default="false" type="long" usage="DATE" formatindex="30">
+      <FormatCode>NNNND "de" MMMM "de" YYYY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey18" default="false" type="short" usage="DATE" formatindex="31">
+      <FormatCode>MM-DD</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey19" default="false" type="medium" usage="DATE" formatindex="32">
+      <FormatCode>YY-MM-DD</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey20" default="false" type="medium" usage="DATE" formatindex="33">
+      <FormatCode>YYYY-MM-DD</FormatCode>
+      <DefaultName>ISO 8601 (EN 28601)</DefaultName>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey3" default="false" type="medium" usage="DATE" formatindex="34">
+      <FormatCode>MM/YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey4" default="false" type="medium" usage="DATE" formatindex="35">
+      <FormatCode>DD/MMM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey5" default="false" type="medium" usage="DATE" formatindex="36">
+      <FormatCode>MMMM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey6" default="false" type="medium" usage="DATE" formatindex="37">
+      <FormatCode>QQ YY</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateFormatskey21" default="false" type="medium" usage="DATE" formatindex="38">
+      <FormatCode>WW</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey1" default="true" type="short" usage="TIME" formatindex="39">
+      <FormatCode>HH:MM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey2" default="true" type="medium" usage="TIME" formatindex="40">
+      <FormatCode>HH:MM:SS</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey3" default="false" type="short" usage="TIME" formatindex="41">
+      <FormatCode>HH:MM AM/PM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey4" default="false" type="medium" usage="TIME" formatindex="42">
+      <FormatCode>HH:MM:SS AM/PM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey5" default="false" type="medium" usage="TIME" formatindex="43">
+      <FormatCode>[HH]:MM:SS</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey6" default="false" type="short" usage="TIME" formatindex="44">
+      <FormatCode>MM:SS,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="TimeFormatskey7" default="false" type="medium" usage="TIME" formatindex="45">
+      <FormatCode>[HH]:MM:SS,00</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateTimeFormatskey1" default="true" type="medium" usage="DATE_TIME" formatindex="46">
+      <FormatCode>DD/MM/YY HH:MM</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateTimeFormatskey2" default="false" type="medium" usage="DATE_TIME" formatindex="47">
+      <FormatCode>DD/MM/YYYY HH:MM:SS</FormatCode>
+    </FormatElement>
+    <FormatElement msgid="DateTimeFormatskey3" default="false" type="medium" usage="DATE_TIME" formatindex="50">
+      <FormatCode>DD/MM/YYYY HH:MM</FormatCode>
+    </FormatElement>
+  </LC_FORMAT>
+  <LC_COLLATION ref="en_US" />
+  <LC_SEARCH ref="en_US"/>
+  <LC_INDEX>
+    <IndexKey phonetic="false" default="true" unoid="alphanumeric">A-N Ñ O Ó P-Z</IndexKey>
+    <UnicodeScript>0</UnicodeScript>
+    <UnicodeScript>1</UnicodeScript>
+    <FollowPageWord> s.</FollowPageWord>
+    <FollowPageWord> ss.</FollowPageWord>
+  </LC_INDEX>
+  <LC_CALENDAR>
+    <Calendar unoid="gregorian" default="true">
+      <DaysOfWeek>
+        <Day>
+          <DayID>sun</DayID>
+          <DefaultAbbrvName>dom</DefaultAbbrvName>
+          <DefaultFullName>domingo</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>mon</DayID>
+          <DefaultAbbrvName>lun</DefaultAbbrvName>
+          <DefaultFullName>lunes</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>tue</DayID>
+          <DefaultAbbrvName>mar</DefaultAbbrvName>
+          <DefaultFullName>martes</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>wed</DayID>
+          <DefaultAbbrvName>mié</DefaultAbbrvName>
+          <DefaultFullName>miércoles</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>thu</DayID>
+          <DefaultAbbrvName>jue</DefaultAbbrvName>
+          <DefaultFullName>jueves</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>fri</DayID>
+          <DefaultAbbrvName>vie</DefaultAbbrvName>
+          <DefaultFullName>viernes</DefaultFullName>
+        </Day>
+        <Day>
+          <DayID>sat</DayID>
+          <DefaultAbbrvName>sáb</DefaultAbbrvName>
+          <DefaultFullName>sábado</DefaultFullName>
+        </Day>
+      </DaysOfWeek>
+      <MonthsOfYear>
+        <Month>
+          <MonthID>jan</MonthID>
+          <DefaultAbbrvName>ene</DefaultAbbrvName>
+          <DefaultFullName>enero</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>feb</MonthID>
+          <DefaultAbbrvName>feb</DefaultAbbrvName>
+          <DefaultFullName>febrero</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>mar</MonthID>
+          <DefaultAbbrvName>mar</DefaultAbbrvName>
+          <DefaultFullName>marzo</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>apr</MonthID>
+          <DefaultAbbrvName>abr</DefaultAbbrvName>
+          <DefaultFullName>abril</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>may</MonthID>
+          <DefaultAbbrvName>may</DefaultAbbrvName>
+          <DefaultFullName>mayo</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>jun</MonthID>
+          <DefaultAbbrvName>jun</DefaultAbbrvName>
+          <DefaultFullName>junio</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>jul</MonthID>
+          <DefaultAbbrvName>jul</DefaultAbbrvName>
+          <DefaultFullName>julio</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>aug</MonthID>
+          <DefaultAbbrvName>ago</DefaultAbbrvName>
+          <DefaultFullName>agosto</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>sep</MonthID>
+          <DefaultAbbrvName>sep</DefaultAbbrvName>
+          <DefaultFullName>septiembre</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>oct</MonthID>
+          <DefaultAbbrvName>oct</DefaultAbbrvName>
+          <DefaultFullName>octubre</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>nov</MonthID>
+          <DefaultAbbrvName>nov</DefaultAbbrvName>
+          <DefaultFullName>noviembre</DefaultFullName>
+        </Month>
+        <Month>
+          <MonthID>dec</MonthID>
+          <DefaultAbbrvName>dic</DefaultAbbrvName>
+          <DefaultFullName>diciembre</DefaultFullName>
+        </Month>
+      </MonthsOfYear>
+      <Eras>
+        <Era>
+          <EraID>bc</EraID>
+          <DefaultAbbrvName>a.C.</DefaultAbbrvName>
+          <DefaultFullName>a.C.</DefaultFullName>
+        </Era>
+        <Era>
+          <EraID>ad</EraID>
+          <DefaultAbbrvName>d.C.</DefaultAbbrvName>
+          <DefaultFullName>d.C.</DefaultFullName>
+        </Era>
+      </Eras>
+      <StartDayOfWeek>
+        <DayID>mon</DayID>
+      </StartDayOfWeek>
+      <MinimalDaysInFirstWeek>1</MinimalDaysInFirstWeek>
+    </Calendar>
+  </LC_CALENDAR>
+  <LC_CURRENCY>
+    <Currency default="true" usedInCompatibleFormatCodes="true">
+      <CurrencyID>EUR</CurrencyID>
+      <CurrencySymbol>€</CurrencySymbol>
+      <BankSymbol>EUR</BankSymbol>
+      <CurrencyName>euro</CurrencyName>
+      <DecimalPlaces>2</DecimalPlaces>
+    </Currency>
+  </LC_CURRENCY>
+  <LC_TRANSLITERATION ref="es_ES"/>
+  <LC_MISC>
+    <ReservedWords>
+      <trueWord>verdadero</trueWord>
+      <falseWord>falso</falseWord>
+      <quarter1Word>1er trimestre</quarter1Word>
+      <quarter2Word>2º trimestre</quarter2Word>
+      <quarter3Word>3er trimestre</quarter3Word>
+      <quarter4Word>4º trimestre</quarter4Word>
+      <aboveWord>arriba</aboveWord>
+      <belowWord>abajo</belowWord>
+      <quarter1Abbreviation>T1</quarter1Abbreviation>
+      <quarter2Abbreviation>T2</quarter2Abbreviation>
+      <quarter3Abbreviation>T3</quarter3Abbreviation>
+      <quarter4Abbreviation>T4</quarter4Abbreviation>
+    </ReservedWords>
+  </LC_MISC>
+  <LC_NumberingLevel ref="es_ES"/>
+  <LC_OutLineNumberingLevel ref="es_ES"/>
+</Locale>
diff --git a/i18npool/source/localedata/localedata.cxx b/i18npool/source/localedata/localedata.cxx
index f4b66802c906..b17dec7c6463 100644
--- a/i18npool/source/localedata/localedata.cxx
+++ b/i18npool/source/localedata/localedata.cxx
@@ -128,6 +128,7 @@ constexpr struct {
     { "es_VE",  DataLocaleLibrary::ES },
     { "gl_ES",  DataLocaleLibrary::ES },
     { "oc_ES_aranes",  DataLocaleLibrary::ES },
+    { "ext_ES", DataLocaleLibrary::ES },
 
     { "de_DE",  DataLocaleLibrary::EURO },
     { "de_AT",  DataLocaleLibrary::EURO },
diff --git a/include/i18nlangtag/lang.h b/include/i18nlangtag/lang.h
index fdb56ed3a34c..7672cf85582f 100644
--- a/include/i18nlangtag/lang.h
+++ b/include/i18nlangtag/lang.h
@@ -796,6 +796,7 @@ namespace o3tl
 #define LANGUAGE_USER_ABKHAZ                LanguageType(0x06B4)
 #define LANGUAGE_USER_ENGLISH_GUYANA        LanguageType(0xBC09)  /* makeLangID( 0x2F, getPrimaryLanguage( LANGUAGE_ENGLISH_UK)) */
 #define LANGUAGE_USER_GRONINGS              LanguageType(0x06B5)
+#define LANGUAGE_USER_EXTREMADURAN          LanguageType(0x06B6)
 
 
 /* XXX Add new user defined LCIDs ^^^ there.