diff --git a/app/config/openapi.js b/app/config/openapi.js
index f044b01..66abdc8 100644
--- a/app/config/openapi.js
+++ b/app/config/openapi.js
@@ -529,6 +529,30 @@ const spec = {
                 responses: { 200: { description: 'Archived' }, 404: { description: 'Not found' }, 403: { description: 'Auth failure' } },
             },
         },
+        '/v1/timeentry/export.csv': {
+            get: {
+                summary: 'CSV export of time entries (invoicing-friendly)',
+                description:
+                    'text/csv response with attachment Content-Disposition. ' +
+                    'Same filter set as bycompany (customerId, from, to) plus a ' +
+                    'master-only `companyId` requirement. 5000-row hard cap; ' +
+                    'oversize results append `# truncated…` comment row.',
+                security: [{ authKey: [] }],
+                parameters: [
+                    { name: 'companyId', in: 'query', schema: { type: 'integer' }, description: 'Required for master keys.' },
+                    { name: 'customerId', in: 'query', schema: { type: 'integer' } },
+                    { name: 'from', in: 'query', schema: { type: 'string', format: 'date-time' } },
+                    { name: 'to', in: 'query', schema: { type: 'string', format: 'date-time' } },
+                    { name: 'limit', in: 'query', schema: { type: 'integer', default: 5000, maximum: 5000 } },
+                    { name: 'offset', in: 'query', schema: { type: 'integer', default: 0 } },
+                ],
+                responses: {
+                    200: { description: 'CSV body', content: { 'text/csv': { schema: { type: 'string' } } } },
+                    400: { description: 'Master without companyId' },
+                    403: { description: 'Missing authKey or cross-tenant export attempt' },
+                },
+            },
+        },
         '/v1/timeentry/bycompany/{id}': {
             get: {
                 summary: 'List time entries for a company',
diff --git a/app/controllers/timeentrycontroller.js b/app/controllers/timeentrycontroller.js
index b70a813..f4f53e0 100644
--- a/app/controllers/timeentrycontroller.js
+++ b/app/controllers/timeentrycontroller.js
@@ -272,5 +272,129 @@ exports.remove = async (req, res) => {
     }
 };
 
+/**
+ * GET /v1/timeentry/export.csv?companyId=&customerId=&from=&to=
+ *
+ * CSV dump of time entries. The natural invoicing flow:
+ *   - filter by customer + date range
+ *   - export rows
+ *   - feed into spreadsheet / accounting tool
+ *
+ * Auth shape mirrors /v1/customer/export.csv: master must specify
+ * companyId, non-master is auto-scoped. Same 5000-row cap with the
+ * trailing `# truncated` comment if exceeded.
+ *
+ * Date range is permissive on bad input (silent drop) to match the
+ * existing listByCompany behavior — a typo'd `from` query param
+ * shouldn't 400 a long-running export script.
+ */
+exports.exportCsv = async (req, res) => {
+    const authKey = req.get('authKey');
+    if (!authKey) {
+        return res.status(403).json({ message: "Authorization key not sent." });
+    }
+
+    let isMasterKey;
+    try {
+        isMasterKey = await IsMaster(authKey);
+    } catch (error) {
+        log.error({ err: error }, 'IsMaster failed');
+        return res.status(500).json({ message: "Error!", error: String(error) });
+    }
+
+    let effectiveCompanyId;
+    if (isMasterKey) {
+        const qCompanyId = Number(req.query.companyId);
+        if (!Number.isInteger(qCompanyId) || qCompanyId <= 0) {
+            return res.status(400).json({
+                message: "Master keys must specify companyId on export.csv.",
+            });
+        }
+        effectiveCompanyId = qCompanyId;
+    } else {
+        let authKeyCompanyId;
+        try {
+            authKeyCompanyId = await GetCompanyId(authKey);
+        } catch (error) {
+            log.error({ err: error }, 'GetCompanyId failed');
+            return res.status(500).json({ message: "Error!", error: String(error) });
+        }
+        if (authKeyCompanyId === -1) {
+            return res.status(403).json({ message: "Invalid Authorization Key." });
+        }
+        const qCompanyId = req.query.companyId !== undefined ? Number(req.query.companyId) : null;
+        if (qCompanyId !== null && qCompanyId !== authKeyCompanyId) {
+            return res.status(403).json({
+                message: "Cannot export time entries for a company you do not belong to.",
+            });
+        }
+        effectiveCompanyId = authKeyCompanyId;
+    }
+
+    const where = { teCompId: effectiveCompanyId, teArch: false };
+    const customerId = Number(req.query.customerId);
+    if (Number.isInteger(customerId) && customerId > 0) {
+        where.teCustId = customerId;
+    }
+    const Op = db.Sequelize && db.Sequelize.Op;
+    if (Op && req.query.from) {
+        where.teStartedAt = Object.assign(where.teStartedAt || {}, { [Op.gte]: req.query.from });
+    }
+    if (Op && req.query.to) {
+        where.teStartedAt = Object.assign(where.teStartedAt || {}, { [Op.lte]: req.query.to });
+    }
+
+    const HARD_CAP = 5000;
+    const requestedLimit = parseInt(req.query.limit, 10);
+    const limit = Number.isInteger(requestedLimit) && requestedLimit > 0
+        ? Math.min(requestedLimit, HARD_CAP)
+        : HARD_CAP;
+    const requestedOffset = parseInt(req.query.offset, 10);
+    const offset = Number.isInteger(requestedOffset) && requestedOffset >= 0
+        ? requestedOffset
+        : 0;
+
+    let rows;
+    try {
+        rows = await TimeEntry.findAll({
+            where,
+            limit: limit + 1,
+            offset,
+            order: [['teStartedAt', 'DESC']],
+        });
+    } catch (error) {
+        log.error({ err: error }, 'TimeEntry.findAll for CSV export failed');
+        return res.status(500).json({ message: "Error!", error: String(error) });
+    }
+
+    const truncated = rows.length > limit;
+    if (truncated) rows = rows.slice(0, limit);
+
+    const FIELDS = [
+        'teId', 'teCustId', 'teCompId',
+        'teStartedAt', 'teEndedAt', 'teMinutes',
+        'teBillable', 'teDescription',
+    ];
+    const escape = (val) => {
+        if (val === null || val === undefined) return '""';
+        // Date instances serialize to ISO; everything else .toString().
+        const s = (val instanceof Date) ? val.toISOString() : String(val);
+        return '"' + s.replace(/"/g, '""') + '"';
+    };
+    const lines = [];
+    lines.push(FIELDS.join(','));
+    for (const r of rows) {
+        lines.push(FIELDS.map((f) => escape(r[f])).join(','));
+    }
+    if (truncated) {
+        lines.push(`# truncated at ${limit} rows; re-call with offset=${offset + limit} to continue`);
+    }
+    const body = lines.join('\r\n') + '\r\n';
+    res.setHeader('Content-Type', 'text/csv; charset=utf-8');
+    res.setHeader('Content-Disposition',
+        `attachment; filename="timeentries-company-${effectiveCompanyId}.csv"`);
+    return res.status(200).send(body);
+};
+
 // Exposed for unit testing.
 exports._internals = { computeMinutes, IsMaster, GetCompanyId };
diff --git a/app/routers/router.js b/app/routers/router.js
index 272003b..211087b 100644
--- a/app/routers/router.js
+++ b/app/routers/router.js
@@ -123,6 +123,11 @@ router.delete(
     v.params(timeEntrySchemas.intIdParam),
     timeEntry.remove,
 );
+router.get(
+    '/v1/timeentry/export.csv',
+    v.query(timeEntrySchemas.exportCsvQuery),
+    timeEntry.exportCsv,
+);
 
 // v1 worker routes.
 router.post(
diff --git a/app/schemas/timeentry.schema.js b/app/schemas/timeentry.schema.js
index 477ff36..ab041a5 100644
--- a/app/schemas/timeentry.schema.js
+++ b/app/schemas/timeentry.schema.js
@@ -48,6 +48,22 @@ const updateTimeEntryBody = z.object({
     message: 'Unexpected field in body. Whitelist: teDescription, teStartedAt, teEndedAt, teBillable.',
 });
 
+/**
+ * GET /v1/timeentry/export.csv query schema. Like listByCompanyQuery
+ * but adds companyId (required for master) and bumps the limit cap
+ * to 5000 to match the CSV body's hard cap.
+ */
+const exportCsvQuery = z.object({
+    companyId: z.coerce.number().int().positive().optional(),
+    customerId: z.coerce.number().int().positive().optional(),
+    from: isoDatetime.optional(),
+    to: isoDatetime.optional(),
+    limit: z.coerce.number().int().positive().max(5000).optional(),
+    offset: z.coerce.number().int().nonnegative().optional(),
+}).strict({
+    message: 'Unexpected query parameter. Allowed: companyId, customerId, from, to, limit, offset.',
+});
+
 const listByCompanyQuery = z.object({
     customerId: z.coerce.number().int().positive().optional(),
     from: isoDatetime.optional(),
@@ -63,4 +79,5 @@ module.exports = {
     createTimeEntryBody,
     updateTimeEntryBody,
     listByCompanyQuery,
+    exportCsvQuery,
 };
diff --git a/tests/api/timeentry-export-csv.test.js b/tests/api/timeentry-export-csv.test.js
new file mode 100644
index 0000000..2cbbbaa
--- /dev/null
+++ b/tests/api/timeentry-export-csv.test.js
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Aaron K. Clark
+//
+// HTTP tests for GET /v1/timeentry/export.csv.
+
+import { describe, test, expect, vi, beforeAll } from 'vitest';
+import request from 'supertest';
+import express from 'express';
+
+vi.mock('../../app/config/db.config.js', () => ({
+    sequelize: {
+        query: vi.fn().mockResolvedValue([]),
+        QueryTypes: { SELECT: 'SELECT' },
+    },
+    Sequelize: { Op: {} },
+    Customer: {}, TimeEntry: {
+        findAll: vi.fn().mockResolvedValue([]),
+        findByPk: vi.fn(),
+        create: vi.fn(),
+    },
+    Worker: {}, BillingType: {}, InventoryItem: {},
+    Company: {}, Job: {}, Invoice: {}, CustomerPayment: {},
+    InvoiceJob: {}, ProductEntry: {}, VersionInfo: {},
+    PurchaseOrderVendor: {}, PurchaseOrderHeader: {}, PurchaseOrderLine: {},
+    InventoryTransaction: {},
+    ApiKey: {}, ApiMaster: {},
+}));
+
+let app;
+
+beforeAll(async () => {
+    const router = (await import('../../app/routers/router.js')).default
+        || require('../../app/routers/router.js');
+    app = express();
+    app.use(express.json());
+    app.use('/', router);
+});
+
+describe('GET /v1/timeentry/export.csv auth contract', () => {
+    test('returns 403 when authKey header is missing', async () => {
+        const res = await request(app).get('/v1/timeentry/export.csv');
+        expect(res.status).toBe(403);
+    });
+});
+
+describe('GET /v1/timeentry/export.csv query validation', () => {
+    test('unknown query param is rejected', async () => {
+        const res = await request(app)
+            .get('/v1/timeentry/export.csv?bogus=1')
+            .set('authKey', 'any');
+        expect(res.status).toBe(400);
+    });
+
+    test('limit > 5000 rejected', async () => {
+        const res = await request(app)
+            .get('/v1/timeentry/export.csv?limit=10000')
+            .set('authKey', 'any');
+        expect(res.status).toBe(400);
+    });
+
+    test('bad ISO datetime in from rejected', async () => {
+        const res = await request(app)
+            .get('/v1/timeentry/export.csv?from=tomorrow')
+            .set('authKey', 'any');
+        expect(res.status).toBe(400);
+    });
+
+    test('well-formed query passes schema', async () => {
+        const res = await request(app)
+            .get('/v1/timeentry/export.csv?customerId=1&from=2026-01-01T00:00:00Z&to=2026-02-01T00:00:00Z&limit=100')
+            .set('authKey', 'any');
+        // Past zod gate; auth-fallback may return whatever, just not 400 from schema.
+        // (Could be 403 or 500 from DB-broken path.)
+        expect(res.status).not.toBe(404);
+    });
+});
+
+describe('GET /v1/timeentry/export.csv route mounting', () => {
+    test('route is mounted (not treated as /:id)', async () => {
+        const res = await request(app)
+            .get('/v1/timeentry/export.csv')
+            .set('authKey', 'any');
+        // Either CSV (success) or JSON error from handler — both prove
+        // the dedicated handler ran, not the :id route's intIdParam.
+        if (res.headers['content-type']?.includes('text/csv')) {
+            // success path — fine
+        } else {
+            expect(res.body).toBeTypeOf('object');
+            expect(res.body.message).toBeDefined();
+        }
+    });
+});