diff --git a/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/controller/ReportCalculationController.kt b/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/controller/ReportCalculationController.kt
index 48aac5f..e009383 100644
--- a/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/controller/ReportCalculationController.kt
+++ b/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/controller/ReportCalculationController.kt
@@ -8,6 +8,7 @@ import com.aamdigital.aambackendservice.reporting.report.core.ReportingStorage
 import com.aamdigital.aambackendservice.reporting.reportcalculation.core.CreateReportCalculationRequest
 import com.aamdigital.aambackendservice.reporting.reportcalculation.core.CreateReportCalculationResult
 import com.aamdigital.aambackendservice.reporting.reportcalculation.core.CreateReportCalculationUseCase
+import com.aamdigital.aambackendservice.reporting.reportcalculation.dto.ReportCalculationData
 import com.aamdigital.aambackendservice.reporting.reportcalculation.dto.ReportCalculationDto
 import com.aamdigital.aambackendservice.reporting.storage.DefaultReportStorage
 import org.springframework.core.io.buffer.DataBuffer
@@ -125,7 +126,7 @@ class ReportCalculationController(
 
                         val prefix = """
                             { 
-                                "_id": "${calculationId}_data.json",
+                                "id": "${calculationId}_data.json",
                                 "report": {
                                     "id": "${calculation.report.id}"
                                 },
@@ -168,6 +169,15 @@ class ReportCalculationController(
         startDate = it.calculationStarted,
         endDate = it.calculationCompleted,
         args = it.args,
-        attachments = it.attachments,
+        data = toReportCalculationData(it),
     )
+
+    private fun toReportCalculationData(it: ReportCalculation): ReportCalculationData? {
+        val attachment = it.attachments["data.json"] ?: return null
+        return ReportCalculationData(
+            contentType = attachment.contentType,
+            hash = attachment.digest,
+            length = attachment.length
+        )
+    }
 }
diff --git a/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/dto/ControllerDtos.kt b/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/dto/ControllerDtos.kt
index 442c650..f1aa028 100644
--- a/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/dto/ControllerDtos.kt
+++ b/application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/reporting/reportcalculation/dto/ControllerDtos.kt
@@ -1,6 +1,5 @@
 package com.aamdigital.aambackendservice.reporting.reportcalculation.dto
 
-import com.aamdigital.aambackendservice.couchdb.dto.AttachmentMetaData
 import com.aamdigital.aambackendservice.domain.DomainReference
 import com.aamdigital.aambackendservice.reporting.domain.ReportCalculationStatus
 
@@ -14,7 +13,13 @@ data class ReportCalculationDto(
     var startDate: String? = null,
     var endDate: String? = null,
     var args: Map<String, String>,
-    var attachments: Map<String, AttachmentMetaData> = emptyMap(),
+    var data: ReportCalculationData?,
+)
+
+data class ReportCalculationData(
+    val contentType: String,
+    val hash: String,
+    val length: Number,
 )
 
 /**
diff --git a/application/aam-backend-service/src/test/resources/cucumber/features/reporting/reportcalculation/fetch-calculation-data.feature b/application/aam-backend-service/src/test/resources/cucumber/features/reporting/reportcalculation/fetch-calculation-data.feature
index 0a7878d..570cd74 100644
--- a/application/aam-backend-service/src/test/resources/cucumber/features/reporting/reportcalculation/fetch-calculation-data.feature
+++ b/application/aam-backend-service/src/test/resources/cucumber/features/reporting/reportcalculation/fetch-calculation-data.feature
@@ -10,7 +10,7 @@ Feature: the report calculation data endpoint persist to database
         When the client calls GET /v1/reporting/report-calculation/ReportCalculation:1/data
         Then the client receives an json object
         Then the client receives status code of 200
-        Then the client receives value ReportCalculation:1_data.json for property _id
+        Then the client receives value ReportCalculation:1_data.json for property id
 
     # ReportCalculation not available
     Scenario: client makes call to GET /reporting/report-calculation/ReportCalculation:42/data and receives NotFound
diff --git a/docs/api-specs/reporting-api-v1.yaml b/docs/api-specs/reporting-api-v1.yaml
index 98ae81c..7597820 100644
--- a/docs/api-specs/reporting-api-v1.yaml
+++ b/docs/api-specs/reporting-api-v1.yaml
@@ -482,15 +482,32 @@ components:
         id:
           type: string
           format: uuid
-        start_date:
+        report:
+          type: object
+          properties:
+            id:
+              type: string
+              format: uuid
+        status:
+          type: string
+          description: Current status of the run
+          enum:
+            - PENDING
+            - RUNNING
+            - FINISHED_SUCCESS
+            - FINISHED_ERROR
+        startDate:
           type: string
+          description: The Date, the calculation starts processing the query
           example: date
-        end_date:
+        endDate:
           type: string
+          description: The Date, the calculation finished processing and the data is available
           example: date
           nullable: true
-        params:
+        args:
           type: object
+          description: Input arguments will be injected into the sql query
           properties:
             from:
               type: string
@@ -502,14 +519,15 @@ components:
               description: optional end date filtering data included in the report. If no date is given here, all data (possibly filtered by the "from" date) is included. The field considered for date filtering are defined in each report's query specifically.
               format: date
               nullable: true
-        status:
-          type: string
-          description: Current status of the run
-          enum:
-            - PENDING
-            - RUNNING
-            - FINISHED_SUCCESS
-            - FINISHED_ERROR
+        data:
+          type: object
+          properties:
+            contentType:
+              type: string
+            hash:
+              type: string
+            length:
+              type: number
 
     ReportData:
       type: object