A

Stock Gains Tax Auto-Calculator

4.05

Derivation Chain

Step 1 Stock market surge + large-scale profit realization
→
Step 2 Capital gains tax and comprehensive financial income tax filing demand
→
Step 3 Automated stock tax calculation and optimization simulation for individual investors

Problem

With KOSPI surpassing 6,300, major shareholders (holding $740,000+ per stock) and overseas stock investors must file capital gains tax, while those exceeding $15,000 in financial income face comprehensive taxation. Manually consolidating trade records across 3–4 brokerages and calculating taxes takes an average of 4–8 hours. Hiring a tax accountant costs $220–$740 per case, and investors who miss tax optimization strategies (staggered selling, loss offsetting, etc.) overpay an estimated $370–$1,500 on average.

Solution

Users upload trade history exported as Excel/CSV from brokerage MTS/HTS platforms. The system auto-calculates capital gains tax and comprehensive financial income tax, then simulates tax differences across optimization scenarios including staggered selling, loss offsetting, and spousal gift-then-sell strategies. Includes filing deadline reminders and auto-generated HomeTax (Korean IRS) return drafts.

Target: Individual investors aged 30–60 with $74,000+ in investments using 2+ brokerages, especially overseas stock investors
Revenue Model: Basic calculation Free, Premium (tax optimization simulation + return generation) at $36/account/year, tax accountant referral fee at $37 Per Transaction
Ecosystem Role: Infrastructure
MVP Estimate: 2_weeks

NUMR-V Scores

N Novelty
2.0/5
U Urgency
5.0/5
M Market
5.0/5
R Realizability
4.0/5
V Validation
4.0/5
NUMR-V Scoring System
N Novelty1-5How uncommon the service is in market context.
U Urgency1-5How urgently users need this problem solved now.
M Market1-5Market size and growth potential from proxy indicators.
R Realizability1-5Buildability for a small team with realistic constraints.
V Validation1-5Validation signal quality from competition and demand data.
Each dimension is scored 1-5 and weighted into grade S/A/B/C/D.
SaaS N=.15 U=.20 M=.15 R=.30 V=.20 Senior N=.25 U=.25 M=.05 R=.30 V=.15

Feasibility (70%)

Tech Complexity
29.3/40
Data Availability
20.8/25
MVP Timeline
20.0/20
API Bonus
0.0/15
Feasibility Breakdown
Tech Complexity/ 40Difficulty of core implementation stack.
Data Availability/ 25Practical availability and cost of required data.
MVP Timeline/ 20Expected time to ship a usable MVP.
API Bonus/ 15Bonus for viable public API leverage.
Total 100 points; below 50% is filtered out.

Market Validation (60/100)

Competition
8.0/20
Market Demand
6.2/20
Timing
16.0/20
Revenue Signals
10.5/15
Pick-Axe Fit
12.0/15
Solo Buildability
7.0/10
Validation Breakdown
Competition/ 20Signal quality from competitor landscape.
Market Demand/ 20Demand proxies from search and mention patterns.
Timing/ 20Fit with current shifts in tech, behavior, and regulation.
Revenue Signals/ 15Reference evidence for monetization viability.
Pick-Axe Fit/ 15How well the concept serves participants in a trend.
Solo Buildability/ 10Practicality for lean-team implementation.
Total 100 points; below 50 is filtered out.

Technical Requirements

Backend [medium] Frontend [medium] Data Pipeline [low]
Dashboard