diff --git a/website/src/lib/oasst_api_client.ts b/website/src/lib/oasst_api_client.ts
index d48a987c..de58ae71 100644
--- a/website/src/lib/oasst_api_client.ts
+++ b/website/src/lib/oasst_api_client.ts
@@ -1,7 +1,6 @@
-import { JWT } from "next-auth/jwt";
 import type { Message } from "src/types/Conversation";
 import { LeaderboardReply, LeaderboardTimeFrame } from "src/types/Leaderboard";
-import type { BackendUser } from "src/types/Users";
+import type { BackendUser, BackendUserCore } from "src/types/Users";
 
 export class OasstError {
   message: string;
@@ -108,14 +107,10 @@ export class OasstApiClient {
   // TODO return a strongly typed Task?
   // This method is used to store a task in RegisteredTask.task.
   // This is a raw Json type, so we can't use it to strongly type the task.
-  async fetchTask(taskType: string, userToken: JWT): Promise<any> {
+  async fetchTask(taskType: string, user: BackendUserCore): Promise<any> {
     return this.post("/api/v1/tasks/", {
       type: taskType,
-      user: {
-        id: userToken.sub,
-        display_name: userToken.name,
-        auth_method: "local",
-      },
+      user,
     });
   }
 
@@ -140,15 +135,11 @@ export class OasstApiClient {
     messageId: string,
     userMessageId: string,
     content: object,
-    userToken: JWT
+    user: BackendUserCore
   ): Promise<any> {
     return this.post("/api/v1/tasks/interaction", {
       type: updateType,
-      user: {
-        id: userToken.sub,
-        display_name: userToken.name,
-        auth_method: "local",
-      },
+      user,
       task_id: taskId,
       message_id: messageId,
       user_message_id: userMessageId,
diff --git a/website/src/lib/users.ts b/website/src/lib/users.ts
new file mode 100644
index 00000000..2aa8c708
--- /dev/null
+++ b/website/src/lib/users.ts
@@ -0,0 +1,38 @@
+import prisma from "src/lib/prismadb";
+import type { BackendUserCore } from "src/types/Users";
+
+/**
+ * Returns a `BackendUserCore` that can be used for interacting with the Backend service.
+ *
+ * @param {string} id The user's web auth id.
+ *
+ * @return {BackendUserCore} The most specific auth type and id for the user.
+ */
+const getBackendUserCore = async (id: string) => {
+  const user = await prisma.user.findUnique({
+    where: { id },
+    select: {
+      id: true,
+      name: true,
+      accounts: true,
+    },
+  });
+
+  // If there are no linked accounts, just use what we have locally.
+  if (user.accounts.length === 0) {
+    return {
+      id: user.id,
+      display_name: user.name,
+      auth_method: "local",
+    } as BackendUserCore;
+  }
+
+  // Otherwise, use the first linked account that the user created.
+  return {
+    id: user.accounts[0].providerAccountId,
+    display_name: user.name,
+    auth_method: user.accounts[0].provider,
+  } as BackendUserCore;
+};
+
+export { getBackendUserCore };
diff --git a/website/src/pages/api/new_task/[task_type].ts b/website/src/pages/api/new_task/[task_type].ts
index e77c5eb2..c8255b18 100644
--- a/website/src/pages/api/new_task/[task_type].ts
+++ b/website/src/pages/api/new_task/[task_type].ts
@@ -1,6 +1,7 @@
 import { withoutRole } from "src/lib/auth";
 import { oasstApiClient } from "src/lib/oasst_api_client";
 import prisma from "src/lib/prismadb";
+import { getBackendUserCore } from "src/lib/users";
 
 /**
  * Returns a new task created from the Task Backend.  We do a few things here:
@@ -14,9 +15,10 @@ const handler = withoutRole("banned", async (req, res, token) => {
   // Fetch the new task.
   const { task_type } = req.query;
 
+  const user = await getBackendUserCore(token.sub);
   let task;
   try {
-    task = await oasstApiClient.fetchTask(task_type as string, token);
+    task = await oasstApiClient.fetchTask(task_type as string, user);
   } catch (err) {
     console.error(err);
     res.status(500).json(err);
diff --git a/website/src/pages/api/update_task.ts b/website/src/pages/api/update_task.ts
index 02982daa..b9de5c50 100644
--- a/website/src/pages/api/update_task.ts
+++ b/website/src/pages/api/update_task.ts
@@ -2,6 +2,8 @@ import { Prisma } from "@prisma/client";
 import { withoutRole } from "src/lib/auth";
 import { oasstApiClient } from "src/lib/oasst_api_client";
 import prisma from "src/lib/prismadb";
+import { getBackendUserCore } from "src/lib/users";
+import type { BackendUserCore } from "src/types/Users";
 
 /**
  * Stores the task interaction with the Task Backend and then returns the next task generated.
@@ -39,9 +41,10 @@ const handler = withoutRole("banned", async (req, res, token) => {
     },
   });
 
+  const user = await getBackendUserCore(token.sub);
   let newTask;
   try {
-    newTask = await oasstApiClient.interactTask(update_type, taskId, frontendId, interaction.id, content, token);
+    newTask = await oasstApiClient.interactTask(update_type, taskId, frontendId, interaction.id, content, user);
   } catch (err) {
     console.error(JSON.stringify(err));
     return res.status(500).json(err);
diff --git a/website/src/types/Users.ts b/website/src/types/Users.ts
index eeb1903a..39d2a663 100644
--- a/website/src/types/Users.ts
+++ b/website/src/types/Users.ts
@@ -1,7 +1,4 @@
-/**
- * Reports the Backend's knowledge of a user.
- */
-export interface BackendUser {
+export interface BackendUserCore {
   /**
    * The user's unique ID according to the `auth_method`.
    */
@@ -18,7 +15,12 @@ export interface BackendUser {
    *   - local
    */
   auth_method: string;
+}
 
+/**
+ * Reports the Backend's knowledge of a user.
+ */
+export interface BackendUser extends BackendUserCore {
   /**
    * The backend's UUID for this user.
    */