ฟรีแลนซ์? เก็บใบ 50 ทวิ ครบทุกใบ — ส่งคำขอลูกค้าอัตโนมัติ คำนวณ ภงด.90 ได้ตลอดปี ไม่จ่ายภาษีซ้ำ

Source signals

• SIG-20260426-sea-mainland-personal-money-th-freelance-pnd90-50tawi-aggregator: "If you are a freelancer or a consultant working with multiple Thai clients, gathering your 50 Tawi slips becomes a logistical nightmare. Every single client who paid you and withheld the mandatory 3% withholding tax must physically mail or email you a separate 50 Tawi certificate ... If you lose one of these slips, you cannot claim the tax credit ... You will end up paying tax on that income twice."

What we ship

**Core features (MVP)**

• Invoice tracking: log invoices to clients — name, NID/tax ID, gross amount, issue date. Marks expected WHT (3% default, 5% for some professional services)
• 50 ทวิ certificate vault: upload paper photo / email PDF; Claude auto-extracts payer name, amount, WHT, date → matches with invoice → "WHT credit verified"
• **Auto-request workflow**: 30 days after invoice without 50 ทวิ → system sends "Hi! Please send 50 ทวิ for invoice INV-2025-04-12" via LINE OA / email with pre-filled template. Re-requests at 60, 90, 120 days
• Real-time PND 90 estimator: any day of year shows "Based on current invoices + WHT credits, your estimated tax owed: 18,400 THB / refund 2,300 THB"
• Annual report wizard: February — "Preparing your ภงด.90" → sums all invoices + WHT credits + personal deductions (LTF/RMF/SSF, parents allowance, education) → PDF ready for RD e-Filing
• Missing-cert alarm: "ตอนนี้ขาด 3 ใบ 50 ทวิ — ถ้าไม่ได้คืน คุณจะจ่ายภาษีเพิ่ม 5,400 บาท"
• Reverse-flow for small business (PRO): generates 50 ทวิ certs for freelancers you pay (payer side)

**Primary user flow**

1. Landing "ฟรีแลนซ์? เก็บใบ 50 ทวิ ครบทุกใบ" + estimated PND 90 dashboard screenshot

2. LINE Login → quick onboard

3. Add client 1: "ABC Co Ltd, NID 1234567890" → add invoice INV-2025-04-12, 50,000 THB

4. App expects 1,500 THB WHT cert within 30 days

5. Day 31 without 50 ทวิ → auto-request to client via LINE OA

6. Day 33: client replies with 50 ทวิ photo → forwards to our LINE OA → Claude extracts → matches

7. February: wizard "Your PND 90 ready — 8 invoices, 7 50 ทวิ verified, 1 missing (re-request sent), tax owed 12,400 THB" → 1-click PDF

8. Pricing trigger: free up to 5 invoices/year, 49 THB/mo for unlimited; PRO 149 THB/mo — auto-request + reverse generator + e-Filing

**What it looks like**

• **Landing**: TH hero "ฟรีแลนซ์? เก็บใบ 50 ทวิ ครบทุกใบ" + dashboard screenshot "This month: 4 invoices, 3 50 ทวิ verified, 1 pending"
• **Main app screen**: timeline current year invoices, estimated PND 90 widget in big font, missing certs alert, "Send reminder to client" button
• **Output / notification**: LINE Notify "Today you received a new 50 ทวิ from XYZ Co (1,500 THB WHT) — estimated refund now 4,200 THB"

**MVP build plan (11 days)**

• Day 1-2: backend (User, Client, Invoice, Certificate, TaxEstimate), JWT, LINE Login
• Day 3: invoice CRUD + WHT logic + 50 ทวิ matching engine
• Day 4-5: 50 ทวิ image/PDF upload + Claude extraction (handles 4 different TH gov 50 ทวิ template variants)
• Day 6: PND 90 estimator engine (incl. deductions cheatsheet — LTF/RMF/SSF, parent allowance, health insurance)
• Day 7-8: auto-request workflow + LINE Official Account + email fallback (SendGrid)
• Day 9: TH-first landing + Omise subscription
• Day 10: annual PND 90 wizard + PDF generator
• Day 11: deploy CF Pages + Railway, soft launch via freelance Facebook groups + Pantip /tax + LINE Open Chat for freelance designers

Reasoning

ภงด.90 / 50 ทวิ is universal pain for all TH freelancers, but no one builds a centralized solution. FlowAccount, PEAK, Bukku — TH accounting SaaS — target small businesses with full bookkeeping, not solo freelancers with 5 clients. Default workflow — Excel + paper folder + manual LINE reminders — broken but dominant. Our differentiator: **freelancer-first UX**, **auto-request workflow** (main pain point — chasing missing certs), **real-time PND 90 estimator** (you see the year, not just in February). 11-day build is realistic — Claude OCR for 50 ทวิ certs is trivial (4 government template variants), LINE OA setup is publicly documented, PND 90 calc algorithm is known. Pain peaks annually (Feb-March), but effectively makes recurring revenue with "annual subscription" 490 THB/year — user subscribes once and stays because "next PND 90 in 12 months". Long-term retention strong (5-7 years minimum — segment doesn't churn).

Quick competitive read

TH market scan — 0 freelancer-first competitors:

• **FlowAccount, PEAK, Bukku**: TH accounting SaaS, B2B focus, full bookkeeping (~990-2,990 THB/mo). Overkill for solo freelancer
• **iTAX (itax.in.th)**: TH tax calculator, but static — no tracking, no auto-request 50 ทวิ
• **QuickBooks Self-Employed (US)**: conceptual precedent, not TH (no PND 90, no 50 ทวิ workflow)
• **Excel + Google Drive folder**: status quo, dominant
• White-space: **freelancer-first 50 ทวิ collection workflow + real-time PND 90 estimator + auto-request via LINE OA** — none on TH market. Competitive pressure 8/10.

Initial pricing hypothesis

Freemium: up to 5 invoices/year free (try tier). PRO 49 THB/mo or 490 THB/year (cleaner for annual tax cycle) — unlimited invoices + auto-request workflow + Claude OCR. Premium 149 THB/mo — reverse 50 ทวิ generator + RD e-Filing + tax-pro marketplace. **Annual subscription (490 THB/year)** — preferred model: user pays February, stays through next Feb. ARPU $14/year × 10K paying users = 4.9M THB ≈ $140K USD ARR year-2 target.

Distribution hypothesis

Pantip /tax soft-launch by replying to "ฟรีแลนซ์ ยื่น ภงด.90 ยังไง" questions. Facebook groups: "Freelance Bangkok", "IT Freelancer Thailand", "Designer Thailand". LINE Open Chat for creative freelancers. SEO on "50 ทวิ หาย", "ภงด.90 ฟรีแลนซ์", "ขอใบ 50 ทวิ จากลูกค้า". Aommoney.com guest post on freelance tax. Influencer marketing — partnership with TH freelance YouTubers ("Freelance to the Max") in Feb-March.