property-calc

name	property-calc
description	Thai NPA property financial calculator. Computes acquisition costs (transfer fee, SBT, WHT, stamp duty), rental yield, price per sqm/wah/rai, and break-even timeline. Use when evaluating any property's financials.

Property Financial Calculator

Overview

Calculates all financial metrics for Thai NPA property evaluation. Handles Thai-specific transfer taxes, size unit conversions (rai/ngan/wah/sqm), and rental yield analysis.

Usage

Full Analysis with Rent Range (recommended)

# Always use LOW/MID/HIGH rent scenarios instead of single rent estimate
python scripts/calc.py --price 1800000 --appraised 2500000 --sqm 35 \
  --rent-low 9000 --rent-mid 10000 --rent-high 12000 \
  --market-price 62800 --renovation 100000

Full Analysis (single rent)

python scripts/calc.py --price 2500000 --appraised 3500000 --rent 15000 --sqm 35
python scripts/calc.py --price 5000000 --appraised 8000000 --rai 0 --ngan 1 --wah 50 --rent 25000 --renovation 500000

Condo Example

python scripts/calc.py --price 1800000 --appraised 2500000 --sqm 28 --rent 12000 --common-fee 2000

Land Example

python scripts/calc.py --price 10000000 --appraised 15000000 --rai 2 --ngan 1 --wah 0

JSON output (for programmatic use)

python scripts/calc.py --price 2500000 --sqm 35 --rent 15000 --json

LED Auction Round Analysis

# Show price reduction schedule for round 6
python scripts/calc.py --led-round 6 --led-appraised 2600000

# LED analysis + full financial analysis combined
python scripts/calc.py --price 1820000 --appraised 2600000 --led-round 6 --sqm 143.5 --rent 15000

# JSON output of LED analysis
python scripts/calc.py --led-round 3 --led-appraised 5000000 --json

LED Auction Price Reduction Rules (กรมบังคับคดี)

นัด (Round)	Starting Price	Notes
1st	100% of appraised value	Full price
2nd	90%	-10% if unsold
3rd	80%	-20% if unsold
4th+	70% (floor)	Won't go lower

Key points:

• Floor is 70% — price never drops below this regardless of how many rounds fail
• All 6th-round Bangkok NPA condos are already at the floor
• If a property is at floor and still unsold after 6 rounds, the issue is the property itself, not the price

Parameters

Param	Description
--price	Purchase/auction price in baht (required)
--appraised	Appraised value in baht (defaults to purchase price)
--rent	Expected monthly rent in baht
--sqm	Size in square meters (for condos)
--rai	Size in rai
--ngan	Size in ngan
--wah	Size in square wah
--renovation	Estimated renovation cost in baht
--vacancy	Vacancy rate (default: 0.10 = 10%)
--common-fee	Monthly common area fee in baht
--held-over-5y	Flag if held >5 years (0.5% stamp duty instead of 3.3% SBT)
--led-round	LED auction round number (shows price reduction analysis)
--led-appraised	Appraised price for LED analysis (defaults to --appraised)
--rent-low	Low rent estimate (baht/month) — use with --rent-mid and --rent-high
--rent-mid	Mid rent estimate (baht/month)
--rent-high	High rent estimate (baht/month)
--market-price	Market price per sqm or wah (for discount sanity check)
--market-unit	Unit for --market-price: "sqm" (default) or "wah"

Thai Transfer Tax Rates

Tax	Rate	When
Transfer Fee	2%	Always (on appraised value)
Specific Business Tax (SBT)	3.3%	Property held < 5 years
Stamp Duty	0.5%	Property held >= 5 years (replaces SBT)
Withholding Tax (WHT)	1%	Always

NPA auction note: Buyer typically pays transfer fee (2%). SBT/WHT is usually seller's responsibility but varies by auction terms.

Size Conversions

Unit	Square Meters
1 rai	1,600 sqm
1 ngan	400 sqm
1 square wah	4 sqm