diff --git a/libs/common/src/vault/models/request/folder-with-id.request.ts b/libs/common/src/vault/models/request/folder-with-id.request.ts
index 8af890048ba..aecb12a05fc 100644
--- a/libs/common/src/vault/models/request/folder-with-id.request.ts
+++ b/libs/common/src/vault/models/request/folder-with-id.request.ts
@@ -1,12 +1,25 @@
+// FIXME: Update this file to be type safe and remove this and next line
+// @ts-strict-ignore
 import { Folder } from "../domain/folder";
 
 import { FolderRequest } from "./folder.request";
 
 export class FolderWithIdRequest extends FolderRequest {
+  /**
+   * Declared as `string` (not `string | null`) to satisfy the
+   * {@link UserKeyRotationDataProvider}`<TRequest extends { id: string } | { organizationId: string }>`
+   * constraint on `FolderService`.
+   *
+   * At runtime this is `null` for new import folders. PR #17077 enforced strict type-checking on
+   * folder models, changing this assignment to `folder.id ?? ""` — causing the importer to send
+   * `{"id":""}` instead of `{"id":null}`, which the server rejected.
+   * The `|| null` below restores the pre-migration behavior while `@ts-strict-ignore` above
+   * allows the `null` assignment against the `string` declaration.
+   */
   id: string;
 
   constructor(folder: Folder) {
     super(folder);
-    this.id = folder.id ?? "";
+    this.id = folder.id || null;
   }
 }
diff --git a/libs/importer/src/importers/bitwarden/bitwarden-csv-importer.spec.ts b/libs/importer/src/importers/bitwarden/bitwarden-csv-importer.spec.ts
index 8f1a281050f..44ee35568d0 100644
--- a/libs/importer/src/importers/bitwarden/bitwarden-csv-importer.spec.ts
+++ b/libs/importer/src/importers/bitwarden/bitwarden-csv-importer.spec.ts
@@ -120,4 +120,106 @@ describe("BitwardenCsvImporter", () => {
     expect(result.ciphers.length).toBe(1);
     expect(result.ciphers[0].archivedDate).toBeUndefined();
   });
+
+  describe("Individual vault imports with folders", () => {
+    beforeEach(() => {
+      importer.organizationId = null;
+    });
+
+    it("should parse folder and create a folder relationship", async () => {
+      const data =
+        `folder,favorite,type,name,login_uri,login_username,login_password` +
+        `\nSocial,0,login,Facebook,https://facebook.com,user@example.com,password`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.ciphers.length).toBe(1);
+      expect(result.folders.length).toBe(1);
+      expect(result.folders[0].name).toBe("Social");
+      expect(result.folderRelationships).toHaveLength(1);
+      expect(result.folderRelationships[0]).toEqual([0, 0]);
+    });
+
+    it("should deduplicate folders when multiple items share the same folder", async () => {
+      const data =
+        `folder,favorite,type,name,login_uri,login_username,login_password` +
+        `\nSocial,0,login,Facebook,https://facebook.com,user1,pass1` +
+        `\nSocial,0,login,Twitter,https://twitter.com,user2,pass2`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.ciphers.length).toBe(2);
+      expect(result.folders.length).toBe(1);
+      expect(result.folders[0].name).toBe("Social");
+      expect(result.folderRelationships).toHaveLength(2);
+      expect(result.folderRelationships[0]).toEqual([0, 0]);
+      expect(result.folderRelationships[1]).toEqual([1, 0]);
+    });
+
+    it("should create parent folders for nested folder paths", async () => {
+      const data =
+        `folder,favorite,type,name,login_uri,login_username,login_password` +
+        `\nWork/Email,0,login,Gmail,https://gmail.com,user@work.com,pass`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.folders.length).toBe(2);
+      expect(result.folders.map((f) => f.name)).toContain("Work/Email");
+      expect(result.folders.map((f) => f.name)).toContain("Work");
+      expect(result.folderRelationships).toHaveLength(1);
+      expect(result.folderRelationships[0]).toEqual([0, 0]);
+    });
+
+    it("should create no folder or relationship when folder column is empty", async () => {
+      const data =
+        `folder,favorite,type,name,login_uri,login_username,login_password` +
+        `\n,0,login,No Folder Item,https://example.com,user,pass`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.ciphers.length).toBe(1);
+      expect(result.folders.length).toBe(0);
+      expect(result.folderRelationships).toHaveLength(0);
+    });
+  });
+
+  describe("organization collection import", () => {
+    it("should set collectionRelationships mapping ciphers to collections", async () => {
+      const data =
+        `collections,type,name,login_uri,login_username,login_password` +
+        `\ncol1,login,Item1,https://example.com,user1,pass1` +
+        `\ncol2,login,Item2,https://example.com,user2,pass2`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.ciphers.length).toBe(2);
+      expect(result.collections.length).toBe(2);
+      // Each cipher maps to its own collection
+      expect(result.collectionRelationships).toHaveLength(2);
+      expect(result.collectionRelationships[0]).toEqual([0, 0]);
+      expect(result.collectionRelationships[1]).toEqual([1, 1]);
+    });
+
+    it("should deduplicate collections and map both ciphers to the shared collection", async () => {
+      const data =
+        `collections,type,name,login_uri,login_username,login_password` +
+        `\nShared,login,Item1,https://example.com,user1,pass1` +
+        `\nShared,login,Item2,https://example.com,user2,pass2`;
+
+      const result = await importer.parse(data);
+
+      expect(result.success).toBe(true);
+      expect(result.ciphers.length).toBe(2);
+      expect(result.collections.length).toBe(1);
+      expect(result.collections[0].name).toBe("Shared");
+      expect(result.collectionRelationships).toHaveLength(2);
+      expect(result.collectionRelationships[0]).toEqual([0, 0]);
+      expect(result.collectionRelationships[1]).toEqual([1, 0]);
+    });
+  });
 });
diff --git a/libs/importer/src/services/import.service.spec.ts b/libs/importer/src/services/import.service.spec.ts
index 33a1e47a4ce..5f9b3c4b085 100644
--- a/libs/importer/src/services/import.service.spec.ts
+++ b/libs/importer/src/services/import.service.spec.ts
@@ -15,6 +15,8 @@ import { Utils } from "@bitwarden/common/platform/misc/utils";
 import { CollectionId, OrganizationId } from "@bitwarden/common/types/guid";
 import { CipherService } from "@bitwarden/common/vault/abstractions/cipher.service";
 import { FolderService } from "@bitwarden/common/vault/abstractions/folder/folder.service.abstraction";
+import { Folder } from "@bitwarden/common/vault/models/domain/folder";
+import { FolderWithIdRequest } from "@bitwarden/common/vault/models/request/folder-with-id.request";
 import { CipherView } from "@bitwarden/common/vault/models/view/cipher.view";
 import { FolderView } from "@bitwarden/common/vault/models/view/folder.view";
 import { RestrictedItemTypesService } from "@bitwarden/common/vault/services/restricted-item-types.service";
@@ -280,6 +282,25 @@ describe("ImportService", () => {
   });
 });
 
+describe("FolderWithIdRequest", () => {
+  function makeFolder(id: string): Folder {
+    const folder = new Folder();
+    folder.id = id;
+    return folder;
+  }
+
+  it("preserves a real folder id", () => {
+    const guid = "f1a2b3c4-d5e6-7890-abcd-ef1234567890";
+    const request = new FolderWithIdRequest(makeFolder(guid));
+    expect(request.id).toBe(guid);
+  });
+
+  it("sends null when folder id is empty string (new import folder)", () => {
+    const request = new FolderWithIdRequest(makeFolder(""));
+    expect(request.id).toBeNull();
+  });
+});
+
 function createCipher(options: Partial<CipherView> = {}) {
   const cipher = new CipherView();