diff --git a/src/model.ts b/src/model.ts
index 635e895..59d92bf 100644
--- a/src/model.ts
+++ b/src/model.ts
@@ -710,7 +710,7 @@ export class SpraypaintBase {
     relatedModel: SpraypaintBase
   ): boolean {
     const dc = new DirtyChecker(this)
-    return dc.checkRelation(relationName, relatedModel)
+    return !this.isPersisted || dc.checkRelation(relationName, relatedModel)
   }
 
   dup(): this {
diff --git a/src/util/write-payload.ts b/src/util/write-payload.ts
index bc277f9..54e3df0 100644
--- a/src/util/write-payload.ts
+++ b/src/util/write-payload.ts
@@ -123,8 +123,7 @@ export class WritePayload<T extends SpraypaintBase> {
             !this._isNewAndMarkedForDestruction(relatedModels) &&
             (idOnly ||
               this.model.hasDirtyRelation(key, relatedModels) ||
-              relatedModels.isDirty(nested) ||
-              !this.model.isPersisted)
+              relatedModels.isDirty(nested))
           ) {
             data = this._processRelatedModel(relatedModels, nested, idOnly)
           }
diff --git a/test/integration/nested-persistence.test.ts b/test/integration/nested-persistence.test.ts
index 4181b01..5eb00be 100644
--- a/test/integration/nested-persistence.test.ts
+++ b/test/integration/nested-persistence.test.ts
@@ -273,17 +273,6 @@ describe("nested persistence", () => {
       expect(instance.books[0].genre.name).to.eq("name from server")
     })
 
-    describe("when a hasMany relationship has no dirty members", () => {
-      beforeEach(() => {
-        instance.books[0] = new Book()
-      })
-
-      it("should not be sent in the payload", async () => {
-        await instance.save({ with: { books: "genre" } })
-        expect((<any>payloads)[0].data.relationships).to.eq(undefined)
-      })
-    })
-
     describe("when a belongsTo relationship has unpersisted members that are marked for destruction", () => {
       beforeEach(() => {
         instance.books[0].genre.isMarkedForDestruction = true
diff --git a/test/unit/write-payload.test.ts b/test/unit/write-payload.test.ts
index 674ce8e..8805a31 100644
--- a/test/unit/write-payload.test.ts
+++ b/test/unit/write-payload.test.ts
@@ -1,6 +1,6 @@
 import { sinon, expect } from "../test-helper"
 import { WritePayload } from "../../src/util/write-payload"
-import { Person, PersonWithDasherizedKeys, Author, Genre } from "../fixtures"
+import { Person, PersonWithDasherizedKeys, Author, Genre, Book } from "../fixtures"
 
 describe("WritePayload", () => {
   it("Does not serialize number attributes as empty string", () => {
@@ -46,13 +46,10 @@ describe("WritePayload", () => {
     })
   })
 
-  it("sends persisted relationships defined via direct assignment", () => {
+  describe("sends persisted singular relationships defined via", () => {
     const genre = new Genre({ name: "Horror", id: "1" })
     genre.isPersisted = true
-    const author = new Author()
-    author.genre = genre
-    const payload = new WritePayload(author, ["genre"])
-    expect(payload.asJSON()).to.deep.equal({
+    const expectedPayload = {
       data: {
         type: "authors",
         relationships: {
@@ -71,33 +68,59 @@ describe("WritePayload", () => {
           type: "genres"
         }
       ]
+    }
+
+    it("constructor", () => {
+      const author = new Author({ genre: genre })
+      const payload = new WritePayload(author, ["genre"])
+      expect(payload.asJSON()).to.deep.equal(expectedPayload)
+    })
+
+    it("direct assignment", () => {
+      const author = new Author()
+      author.genre = genre
+      const payload = new WritePayload(author, ["genre"])
+      expect(payload.asJSON()).to.deep.equal(expectedPayload)
     })
   })
 
-  it("sends persisted relationships defined via constructor", () => {
-    const genre = new Genre({ name: "Horror", id: "1" })
-    genre.isPersisted = true
-    const author = new Author({ genre })
-    const payload = new WritePayload(author, ["genre"])
-    expect(payload.asJSON()).to.deep.equal({
+  describe("sends persisted plural relationships defined via", () => {
+    const book = new Book({ title: "Horror", id: "1" })
+    book.isPersisted = true
+    const expectedPayload = {
       data: {
         type: "authors",
         relationships: {
-          genre: {
-            data: {
-              id: "1",
-              type: "genres",
-              method: "update"
-            }
+          books: {
+            data: [
+              {
+                id: "1",
+                type: "books",
+                method: "update"
+              }
+            ]
           }
         }
       },
       included: [
         {
           id: "1",
-          type: "genres"
+          type: "books"
         }
       ]
+    }
+
+    it("constructor", () => {
+      const author = new Author({ books: [book] })
+      const payload = new WritePayload(author, ["books"])
+      expect(payload.asJSON()).to.deep.equal(expectedPayload)
+    })
+
+    it("direct assignment", () => {
+      const author = new Author()
+      author.books.push(book)
+      const payload = new WritePayload(author, ["books"])
+      expect(payload.asJSON()).to.deep.equal(expectedPayload)
     })
   })