diff --git a/src/db/index.ts b/src/db/index.ts
index 18b2d2d7..1cb4a29c 100644
--- a/src/db/index.ts
+++ b/src/db/index.ts
@@ -93,6 +93,8 @@ import reportDetail from './models/reportDetail';
 import reportFile from './models/reportFile';
 import reportingWindow from './models/reportingWindow';
 import reportingWindowAssignment from './models/reportingWindowAssignment';
+import serviceModality from './models/serviceModality';
+import serviceModalityAssociation from './models/serviceModalityAssociation';
 import tag from './models/tag';
 import task from './models/task';
 import unit from './models/unit';
@@ -218,6 +220,11 @@ const initializeTables = (masterConn: Knex, replicaConn?: Knex) => ({
   reportFile: reportFile(masterConn, replicaConn),
   reportingWindow: reportingWindow(masterConn, replicaConn),
   reportingWindowAssignment: reportingWindowAssignment(masterConn, replicaConn),
+  serviceModality: serviceModality(masterConn, replicaConn),
+  serviceModalityAssociation: serviceModalityAssociation(
+    masterConn,
+    replicaConn
+  ),
   tag: tag(masterConn, replicaConn),
   task: task(masterConn, replicaConn),
   unit: unit(masterConn, replicaConn),
diff --git a/src/db/models/json/attachment.ts b/src/db/models/json/attachment.ts
index bb5698b3..b31ec247 100644
--- a/src/db/models/json/attachment.ts
+++ b/src/db/models/json/attachment.ts
@@ -4,6 +4,15 @@ import {
   INDICATOR_VALUE as INDICATOR_ATTACHMENT_VALUE,
 } from './indicatorsAndCaseloads';
 
+const COST_BREAKDOWN = t.array(
+  t.exact(
+    t.type({
+      objectId: t.number,
+      cost: t.number,
+    })
+  )
+);
+
 const COST_ATTACHMENT_VALUE = t.intersection([
   t.exact(
     t.type({
@@ -13,23 +22,16 @@ const COST_ATTACHMENT_VALUE = t.intersection([
   t.exact(
     t.partial({
       /**
-       * When necessary, a cost breakdown can be provided with respect to a
-       * particular collection of objects.
-       *
-       * For example, when the object of this attachment is a governing entity,
-       * a breakdown needs to be provided for each of the global clusters,
-       * (even if the governing entity has 0 global clusters)
-       * and the total sum of the breakdown must match the overall cost when
-       * non-empty.
+       * When necessary, a cost breakdown can be provided for each of the global
+       * clusters (even if the governing entity has 0 global clusters), and the
+       * total sum of the breakdown must match the overall cost when non-empty.
        */
-      breakdown: t.array(
-        t.exact(
-          t.type({
-            objectId: t.number,
-            cost: t.number,
-          })
-        )
-      ),
+      breakdownByGlobalCluster: COST_BREAKDOWN,
+      /**
+       * Unlike global cluster breakdown, service modality breakdown
+       * doesn't need to add up to the total cost
+       */
+      breakdownByServiceModality: COST_BREAKDOWN,
       // TODO: delete these properties once we've confirmed that they're not
       // needed for any code that reads cost attachments
       // (they seem to be produced by RPM frontend code related to other types)
diff --git a/src/db/models/serviceModality.ts b/src/db/models/serviceModality.ts
new file mode 100644
index 00000000..02d64d4d
--- /dev/null
+++ b/src/db/models/serviceModality.ts
@@ -0,0 +1,29 @@
+import * as t from 'io-ts';
+
+import { brandedType } from '../../util/io-ts';
+import type { Brand } from '../../util/types';
+import { defineIDModel } from '../util/id-model';
+
+export type ServiceModalityId = Brand<
+  number,
+  { readonly s: unique symbol },
+  'serviceModality.id'
+>;
+
+export const SERVICE_MODALITY_ID = brandedType<number, ServiceModalityId>(
+  t.number
+);
+
+export default defineIDModel({
+  tableName: 'serviceModality',
+  fields: {
+    generated: {
+      id: { kind: 'branded-integer', brand: SERVICE_MODALITY_ID },
+    },
+    required: {
+      name: { kind: 'checked', type: t.string },
+    },
+  },
+  idField: 'id',
+  softDeletionEnabled: false,
+});
diff --git a/src/db/models/serviceModalityAssociation.ts b/src/db/models/serviceModalityAssociation.ts
new file mode 100644
index 00000000..0575d65b
--- /dev/null
+++ b/src/db/models/serviceModalityAssociation.ts
@@ -0,0 +1,20 @@
+import { defineSequelizeModel } from '../util/sequelize-model';
+import { GOVERNING_ENTITY_ID } from './governingEntity';
+import { SERVICE_MODALITY_ID } from './serviceModality';
+
+export default defineSequelizeModel({
+  tableName: 'serviceModalityAssociation',
+  fields: {
+    required: {
+      serviceModalityId: {
+        kind: 'branded-integer',
+        brand: SERVICE_MODALITY_ID,
+      },
+      governingEntityId: {
+        kind: 'branded-integer',
+        brand: GOVERNING_ENTITY_ID,
+      },
+    },
+  },
+  softDeletionEnabled: false,
+});