diff --git a/README.md b/README.md
index 003fba8..d59cf23 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,9 @@
 
 This repository houses the reports API for all Topcoder and Topgear reports on the Topcoder platform.  The reports are pulled directly from live data, not a data warehouse, so they should be up-to-date when they are generated and the response is returned.
 
-All reports will return JSON data with the expected fields for the individual report
+Reports return JSON data by default. Endpoints that support CSV can also return
+CSV when the request sets `Accept: text/csv` (including the Challenges and
+Topcoder report groups).
 
 ## Security
 
diff --git a/scripts/export-member-tax.js b/scripts/export-member-tax.js
index 7b715cf..ad4b8ff 100644
--- a/scripts/export-member-tax.js
+++ b/scripts/export-member-tax.js
@@ -5,7 +5,6 @@ const path = require("path");
 const { Pool } = require("pg");
 
 const CSV_COLUMNS = [
-  "payment.payment_id",
   "payee.handle",
   "payee.email",
   "payee.first_name",
@@ -336,6 +335,11 @@ function writeCsv(outputPath, rows) {
   fs.writeFileSync(outputPath, `${lines.join("\n")}\n`, "utf8");
 }
 
+function toNumberOrZero(value) {
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? parsed : 0;
+}
+
 async function run() {
   const options = parseArgs(process.argv.slice(2));
   if (options.help) {
@@ -436,7 +440,45 @@ async function run() {
       };
     });
 
-    writeCsv(outputPath, mergedRows);
+    const aggregatedByUser = new Map();
+    for (const row of mergedRows) {
+      const userId = String(row.__user_id);
+      const existing = aggregatedByUser.get(userId);
+
+      if (!existing) {
+        aggregatedByUser.set(userId, {
+          ...row,
+          "user_payment.gross_amount": toNumberOrZero(
+            row["user_payment.gross_amount"],
+          ),
+          "user_payment.net_amount": toNumberOrZero(row["user_payment.net_amount"]),
+        });
+        continue;
+      }
+
+      existing["user_payment.gross_amount"] =
+        toNumberOrZero(existing["user_payment.gross_amount"]) +
+        toNumberOrZero(row["user_payment.gross_amount"]);
+      existing["user_payment.net_amount"] =
+        toNumberOrZero(existing["user_payment.net_amount"]) +
+        toNumberOrZero(row["user_payment.net_amount"]);
+    }
+
+    const aggregatedRows = Array.from(aggregatedByUser.values())
+      .map((row) => {
+        const normalized = { ...row };
+        delete normalized.__user_id;
+        delete normalized.__payment_id;
+        delete normalized["payment.payment_id"];
+        return normalized;
+      })
+      .sort((a, b) =>
+        String(a["payee.handle"] ?? "").localeCompare(
+          String(b["payee.handle"] ?? ""),
+        ),
+      );
+
+    writeCsv(outputPath, aggregatedRows);
     console.log(`[member-tax-export] Wrote CSV: ${outputPath}`);
   } finally {
     await Promise.allSettled([mainPool.end(), oldPaymentsPool.end()]);
diff --git a/src/reports/challenges/challenges-reports.controller.ts b/src/reports/challenges/challenges-reports.controller.ts
index f6f78fc..4f2cad7 100644
--- a/src/reports/challenges/challenges-reports.controller.ts
+++ b/src/reports/challenges/challenges-reports.controller.ts
@@ -1,7 +1,14 @@
-import { Controller, Get, Query, UseGuards } from "@nestjs/common";
+import {
+  Controller,
+  Get,
+  Query,
+  UseGuards,
+  UseInterceptors,
+} from "@nestjs/common";
 import {
   ApiBearerAuth,
   ApiOperation,
+  ApiProduces,
   ApiResponse,
   ApiTags,
 } from "@nestjs/swagger";
@@ -11,6 +18,7 @@ import { PaymentsReportResponse } from "../sfdc/sfdc-reports.dto";
 import { Scopes } from "../../auth/decorators/scopes.decorator";
 import { Scopes as AppScopes } from "../../app-constants";
 import { ChallengesReportsService } from "./challenges-reports.service";
+import { CsvResponseInterceptor } from "../../common/interceptors/csv-response.interceptor";
 import { ChallengeRegistrantsQueryDto } from "./dtos/registrants.dto";
 import { ChallengesReportQueryDto } from "./dtos/challenge.dto";
 import {
@@ -19,6 +27,8 @@ import {
 } from "./dtos/submission-links.dto";
 
 @ApiTags("Challenges Reports")
+@ApiProduces("application/json", "text/csv")
+@UseInterceptors(CsvResponseInterceptor)
 @Controller("/challenges")
 export class ChallengesReportsController {
   constructor(private readonly reportsService: ChallengesReportsService) {}
diff --git a/src/reports/challenges/challenges-reports.module.ts b/src/reports/challenges/challenges-reports.module.ts
index 396c13f..e43662b 100644
--- a/src/reports/challenges/challenges-reports.module.ts
+++ b/src/reports/challenges/challenges-reports.module.ts
@@ -1,10 +1,17 @@
 import { Module } from "@nestjs/common";
+import { CsvSerializer } from "src/common/csv/csv-serializer";
 import { SqlLoaderService } from "src/common/sql-loader.service";
+import { CsvResponseInterceptor } from "src/common/interceptors/csv-response.interceptor";
 import { ChallengesReportsController } from "./challenges-reports.controller";
 import { ChallengesReportsService } from "./challenges-reports.service";
 
 @Module({
   controllers: [ChallengesReportsController],
-  providers: [ChallengesReportsService, SqlLoaderService],
+  providers: [
+    ChallengesReportsService,
+    SqlLoaderService,
+    CsvSerializer,
+    CsvResponseInterceptor,
+  ],
 })
 export class ChallengesReportsModule {}