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Downsizing Capital Gains Tax Reverse Calculator

4.30

Derivation Chain

Step 1 Real Estate downsizing decision-making
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Step 2 Capital gains tax as the biggest barrier to downsizing
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Step 3 Reverse-calculating optimal sale timing and method to minimize capital gains tax

Problem

After children move out, couples in their 60s want to sell a $675,000 apartment and downsize to one around $375,000, but the interplay of holding period, residence period, single-home tax exemption requirements, and long-term holding special deduction rates is so complex that they cannot accurately determine 'how much capital gains tax if I sell now' or 'how much I'd save by staying 6 more months.' Real Estate agents cannot provide tax advice, and tax accountant consultations cost $150–$375 per session.

Solution

Users enter acquisition cost, acquisition date, current market value, and residence period on the web, and the tool calculates capital gains tax month-by-month for sale dates from now through 2 years out, suggesting the optimal sale timing. Single-home tax exemption eligibility and long-term holding special deduction rate changes are visualized on a timeline. Post-downsizing surplus fund scenarios (deposits, pension, ETFs) are also integrated.

Target: Ages 58–65, owning one apartment in a metro area, children have moved out, couples considering downsizing
Revenue Model: Basic capital gains tax calculation free; detailed tax optimization scenario + surplus fund strategy Report at $7.40 per transaction; tax accountant referral commission
Ecosystem Role: Supplier
MVP Estimate: 2_weeks

NUMR-V Scores

N Novelty
3.0/5
U Urgency
5.0/5
M Market
4.0/5
R Realizability
5.0/5
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 (68%)

Tech Complexity
29.3/40
Data Availability
19.2/25
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 (57/100)

Competition
8.0/20
Market Demand
6.2/20
Timing
14.0/20
Revenue Signals
10.5/15
Pick-Axe Fit
10.5/15
Solo Buildability
8.0/10
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

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