diff --git a/common/locales/en/api-v3.json b/common/locales/en/api-v3.json
index 0b810c76d1..935fdf2a1d 100644
--- a/common/locales/en/api-v3.json
+++ b/common/locales/en/api-v3.json
@@ -27,5 +27,5 @@
   "positionRequired": "\"position\" is required and must be a number.",
   "cantMoveCompletedTodo": "Can't move a completed todo.",
   "directionUpDown": "\"direction\" is required and must be 'up' or 'down'",
-  "alreadyTagged": "The task is already tagged with give tag."
+  "alreadyTagged": "The task is already tagged with given tag."
 }
diff --git a/test/api/v3/integration/tasks/tags/DELETE-tasks_taskId_tags_tagId.test.js b/test/api/v3/integration/tasks/tags/DELETE-tasks_taskId_tags_tagId.test.js
new file mode 100644
index 0000000000..6fa2c94d68
--- /dev/null
+++ b/test/api/v3/integration/tasks/tags/DELETE-tasks_taskId_tags_tagId.test.js
@@ -0,0 +1,53 @@
+import {
+  generateUser,
+  requester,
+  translate as t,
+} from '../../../../../helpers/api-integration.helper';
+import { v4 as generateUUID } from 'uuid';
+
+describe('DELETE /tasks/:taskId/tags/:tagId', () => {
+  let user, api;
+
+  before(() => {
+    return generateUser().then((generatedUser) => {
+      user = generatedUser;
+      api = requester(user);
+    });
+  });
+
+  it('removes a tag from a task', () => {
+    let tag;
+    let task;
+
+    return api.post('/tasks', {
+      type: 'habit',
+      text: 'Task with tag',
+    }).then(createdTask => {
+      task = createdTask;
+      return api.post('/tags', {name: 'Tag 1'});
+    }).then(createdTag => {
+      tag = createdTag;
+      return api.post(`/tasks/${task._id}/tags/${tag._id}`);
+    }).then(savedTask => {
+      return api.del(`/tasks/${task._id}/tags/${tag._id}`);
+    }).then(() => api.get(`/tasks/${task._id}`))
+    .then(updatedTask => {
+      expect(updatedTask.tags.length).to.equal(0);
+    });
+  });
+
+  it('only deletes existing tags', () => {
+    let task;
+
+    return expect(api.post('/tasks', {
+      type: 'habit',
+      text: 'Task with tag',
+    }).then(createdTask => {
+      return api.del(`/tasks/${createdTask._id}/tags/${generateUUID()}`);
+    })).to.eventually.be.rejected.and.eql({
+      code: 404,
+      error: 'NotFound',
+      message: t('tagNotFound'),
+    });
+  });
+});
diff --git a/test/api/v3/integration/tasks/tags/POST-tasks_taskId_tags_tagId.test.js b/test/api/v3/integration/tasks/tags/POST-tasks_taskId_tags_tagId.test.js
new file mode 100644
index 0000000000..b5e8f4e485
--- /dev/null
+++ b/test/api/v3/integration/tasks/tags/POST-tasks_taskId_tags_tagId.test.js
@@ -0,0 +1,70 @@
+import {
+  generateUser,
+  requester,
+  translate as t,
+} from '../../../../../helpers/api-integration.helper';
+import { v4 as generateUUID } from 'uuid';
+
+describe('POST /tasks/:taskId/tags/:tagId', () => {
+  let user, api;
+
+  before(() => {
+    return generateUser().then((generatedUser) => {
+      user = generatedUser;
+      api = requester(user);
+    });
+  });
+
+  it('adds a tag to a task', () => {
+    let tag;
+    let task;
+
+    return api.post('/tasks', {
+      type: 'habit',
+      text: 'Task with tag',
+    }).then(createdTask => {
+      task = createdTask;
+      return api.post('/tags', {name: 'Tag 1'});
+    }).then(createdTag => {
+      tag = createdTag;
+      return api.post(`/tasks/${task._id}/tags/${tag._id}`);
+    }).then(savedTask => {
+      expect(savedTask.tags[0]).to.equal(tag._id);
+    });
+  });
+
+  it('does not add a tag to a task twice', () => {
+    let tag;
+    let task;
+
+    return expect(api.post('/tasks', {
+      type: 'habit',
+      text: 'Task with tag',
+    }).then(createdTask => {
+      task = createdTask;
+      return api.post('/tags', {name: 'Tag 1'});
+    }).then(createdTag => {
+      tag = createdTag;
+      return api.post(`/tasks/${task._id}/tags/${tag._id}`);
+    }).then(() => {
+      return api.post(`/tasks/${task._id}/tags/${tag._id}`);
+    })).to.eventually.be.rejected.and.eql({
+      code: 400,
+      error: 'BadRequest',
+      message: t('alreadyTagged'),
+    });
+  });
+
+  it('does not add a non existing tag to a task', () => {
+    return expect(api.post('/tasks', {
+      type: 'habit',
+      text: 'Task with tag',
+    }).then((task) => {
+      return api.post(`/tasks/${task._id}/tags/${generateUUID()}`);
+    })).to.eventually.be.rejected.and.eql({
+      code: 400,
+      error: 'BadRequest',
+      message: t('invalidReqParams'),
+    });
+  });
+});
diff --git a/website/src/controllers/api-v3/tasks.js b/website/src/controllers/api-v3/tasks.js
index eec1e28ddb..818362efc9 100644
--- a/website/src/controllers/api-v3/tasks.js
+++ b/website/src/controllers/api-v3/tasks.js
@@ -518,7 +518,7 @@ api.removeChecklistItem = {
  */
 api.addTagToTask = {
   method: 'POST',
-  url: '/tasks/:taskId/tags',
+  url: '/tasks/:taskId/tags/:tagId',
   middlewares: [authWithHeaders()],
   handler (req, res, next) {
     let user = res.locals.user;
@@ -538,7 +538,7 @@ api.addTagToTask = {
       if (!task) throw new NotFound(res.t('taskNotFound'));
       let tagId = req.params.tagId;
 
-      let alreadyTagged = task.tags.indexOf(tagId) === -1;
+      let alreadyTagged = task.tags.indexOf(tagId) !== -1;
       if (alreadyTagged) throw new BadRequest(res.t('alreadyTagged'));
 
       task.tags.push(tagId);
@@ -580,7 +580,7 @@ api.removeTagFromTask = {
     .then((task) => {
       if (!task) throw new NotFound(res.t('taskNotFound'));
 
-      let tagI = _.findIndex(task.tags, {_id: req.params.tagId});
+      let tagI = task.tags.indexOf(req.params.tagId);
       if (tagI === -1) throw new NotFound(res.t('tagNotFound'));
 
       task.tags.splice(tagI, 1);