diff --git a/src/components/TagItem.vue b/src/components/TagItem.vue
index 862771d9cf..8f00736972 100644
--- a/src/components/TagItem.vue
+++ b/src/components/TagItem.vue
@@ -30,7 +30,9 @@
 			</NcColorPicker>
 			<ActionInput
 				v-if="renameTagInput"
-				:value="tag.displayName"
+				v-model="currentTagName"
+				:error="hasError()"
+				:helper-text="errorMessage"
 				@submit="renameTag(tag, $event)" />
 			<ActionText v-if="showSaving">
 				<template #icon>
@@ -70,7 +72,7 @@ import IconEdit from 'vue-material-design-icons/PencilOutline.vue'
 import DeleteIcon from 'vue-material-design-icons/TrashCanOutline.vue'
 import logger from '../logger.js'
 import useMainStore from '../store/mainStore.js'
-import { translateTagDisplayName } from '../util/tag.js'
+import { translateTagDisplayName, validateTag } from '../util/tag.js'
 
 export default {
 	name: 'TagItem',
@@ -106,8 +108,10 @@ export default {
 			tagLabel: true,
 			tagInput: false,
 			showSaving: false,
+			currentTagName: '',
 			renameTagLabel: true,
 			renameTagInput: false,
+			errorMessage: '',
 		}
 	},
 
@@ -115,6 +119,12 @@ export default {
 		...mapStores(useMainStore),
 	},
 
+	watch: {
+		currentTagName() {
+			this.errorMessage = ''
+		},
+	},
+
 	methods: {
 		translateTagDisplayName,
 		deleteTag() {
@@ -141,6 +151,7 @@ export default {
 			this.renameTagLabel = false
 			this.renameTagInput = true
 			this.showSaving = false
+			this.currentTagName = this.tag.displayName
 			this.editColor = this.tag.color
 		},
 
@@ -150,20 +161,30 @@ export default {
 			this.showSaving = false
 		},
 
+		hasError() {
+			return this.errorMessage !== ''
+		},
+
 		async renameTag(tag, event) {
-			this.renameTagInput = false
+			this.currentTagName = this.currentTagName.trim()
+
+			const otherTags = this.mainStore.getTags
+			const valid = validateTag(tag.id, this.currentTagName, otherTags)
+			if (valid !== true) {
+				this.errorMessage = valid
+				return
+			}
+
 			this.showSaving = false
-			const displayName = event.target.querySelector('input[type=text]').value
+			this.errorMessage = ''
 
 			try {
 				await this.mainStore.updateTag({
 					tag,
-					displayName,
+					displayName: this.currentTagName,
 					color: this.tag.color,
 				})
-				this.renameTagLabel = true
-				this.renameTagInput = false
-				this.showSaving = false
+				this.closeEditTag()
 			} catch (error) {
 				showInfo(t('mail', 'An error occurred, unable to rename the tag.'))
 				logger.error('could not rename tag', { error })
diff --git a/src/components/TagModal.vue b/src/components/TagModal.vue
index acd7f13eec..877c82fa52 100644
--- a/src/components/TagModal.vue
+++ b/src/components/TagModal.vue
@@ -61,6 +61,7 @@ import DeleteTagModal from './DeleteTagModal.vue'
 import TagItem from './TagItem.vue'
 import logger from '../logger.js'
 import useMainStore from '../store/mainStore.js'
+import { validateTag } from '../util/tag.js'
 import { hiddenTags } from './tags.js'
 
 function randomColor() {
@@ -99,8 +100,6 @@ export default {
 			tagLabel: true,
 			tagInput: false,
 			showSaving: false,
-			renameTagLabel: true,
-			renameTagInput: false,
 			deleteTagModal: false,
 			tagToDelete: null,
 			color: randomColor(),
@@ -161,19 +160,14 @@ export default {
 				return
 			}
 
-			const displayName = event.target.querySelector('input[type=text]').value
-			if (displayName.toLowerCase() in hiddenTags) {
-				showError(this.t('mail', 'Tag name is a hidden system tag'))
-				return
-			}
-			if (this.mainStore.getTags.some((tag) => tag.displayName === displayName)) {
-				showError(this.t('mail', 'Tag already exists'))
-				return
-			}
-			if (displayName.trim() === '') {
-				showError(this.t('mail', 'Tag name cannot be empty'))
+			const displayName = event.target.querySelector('input[type=text]').value.trim()
+			const otherTags = this.mainStore.getTags
+			const valid = validateTag(null, displayName, otherTags)
+			if (valid !== true) {
+				showError(valid)
 				return
 			}
+
 			try {
 				await this.mainStore.createTag({
 					displayName,
@@ -188,49 +182,6 @@ export default {
 			}
 		},
 
-		convertHex(color, opacity) {
-			if (color.length === 4) {
-				const r = parseInt(color.substring(1, 2), 16)
-				const g = parseInt(color.substring(2, 3), 16)
-				const b = parseInt(color.substring(3, 4), 16)
-				return `rgba(${r}, ${g}, ${b}, ${opacity})`
-			} else {
-				const r = parseInt(color.substring(1, 3), 16)
-				const g = parseInt(color.substring(3, 5), 16)
-				const b = parseInt(color.substring(5, 7), 16)
-				return `rgba(${r}, ${g}, ${b}, ${opacity})`
-			}
-		},
-
-		openEditTag() {
-			this.renameTagLabel = false
-			this.renameTagInput = true
-			this.showSaving = false
-		},
-
-		async renameTag(tag, event) {
-			this.renameTagInput = false
-			this.showSaving = false
-			const displayName = event.target.querySelector('input[type=text]').value
-
-			try {
-				await this.mainStore.updateTag({
-					tag,
-					displayName,
-					color: tag.color,
-				})
-				this.renameTagLabel = true
-				this.renameTagInput = false
-				this.showSaving = false
-			} catch (error) {
-				showInfo(t('mail', 'An error occurred, unable to rename the tag.'))
-				logger.error('could not rename tag', { error })
-				this.renameTagLabel = false
-				this.renameTagInput = false
-				this.showSaving = true
-			}
-		},
-
 		deleteTag(tag) {
 			this.tagToDelete = tag
 			this.deleteTagModal = true
diff --git a/src/util/tag.js b/src/util/tag.js
index 3312f0ca16..ba36264857 100644
--- a/src/util/tag.js
+++ b/src/util/tag.js
@@ -4,6 +4,7 @@
  */
 
 import { translate as t } from '@nextcloud/l10n'
+import { hiddenTags } from '../components/tags.js'
 import { FOLLOW_UP_TAG_LABEL } from '../store/constants.js'
 
 /**
@@ -19,3 +20,21 @@ export function translateTagDisplayName(tag) {
 
 	return tag.displayName
 }
+
+export function validateTag(tagId, tagName, otherTags) {
+	const testableDisplayName = tagName.toLowerCase().trim()
+
+	if (testableDisplayName === '') {
+		return t('mail', 'Tag name cannot be empty')
+	}
+
+	if (Object.keys(hiddenTags).some((tag) => tag.toLowerCase() === testableDisplayName)) {
+		return t('mail', 'Tag name is a hidden system tag')
+	}
+
+	if (otherTags.some((tag) => tagId !== tag.id && tag.displayName.toLowerCase() === testableDisplayName)) {
+		return t('mail', 'Tag already exists')
+	}
+
+	return true
+}