rei-investment-calculator

REI Investment Calculator

Disclaimer: This skill produces financial models for informational and planning purposes only. It is not a substitute for advice from a licensed financial advisor, CPA, or lender. Tax estimates are illustrative only — consult a qualified tax professional before making tax-related decisions. All projections should be independently verified before investing.

Overview

A comprehensive real estate financial modeling engine. Not just mortgage math — this produces full financial models with amortization tables, equity build-up curves, tax benefit estimates, and multi-year projections. Use this after rei-deal-analyzer has confirmed a deal is worth pursuing. Reads prior deal analysis from cloud brain when available to avoid re-entering data.

Analysis types supported:

1. BRRRR (Buy, Rehab, Rent, Refinance, Repeat)
2. Flip profit/loss
3. Buy-and-hold projections (5/10/20/30 year)
4. Refinance analysis (current vs. new terms)
5. Seller finance amortization
6. Lease-option analysis (buyer and seller perspectives)
7. Side-by-side scenario comparison

When This Skill Applies

• User asks for BRRRR analysis on a property
• User wants flip profit/loss calculated
• User asks for buy-and-hold projections over multiple years
• User needs a refinance analysis (current vs. new terms)
• User wants an amortization table or schedule
• User asks about seller finance terms and payment breakdowns
• User needs lease-option analysis (from buyer or seller side)
• User wants to compare two or more investment scenarios side by side
• User asks "what are my returns over 10 years?"
• User wants to see equity build-up over time
• User asks about tax benefits, depreciation, or cost segregation
• User needs a balloon payment or payoff calculation

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Pre-Flight — Investor Preferences

1. Use mcp__cloud-brain__search_notes with query REI preferences
2. If found: Load preferences. Display ⚙️ banner with investor name and key thresholds.
3. If not found: Run preferences setup (same as rei-deal-analyzer). Save to brain/preferences/rei-preferences.md.
4. Check for prior deal analysis: Use mcp__cloud-brain__search_notes with any address/deal slug mentioned. If found, load it and note: "Found saved deal analysis from {date} — pre-loading those inputs."

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Core Calculation Engine

Monthly Payment (fully amortizing)

M = P × [r(1+r)^n] / [(1+r)^n − 1]
P = principal | r = monthly rate (annual/12) | n = total payments (years×12)

Monthly Payment (interest-only)

M = P × r

Remaining Balance at Month X

B(x) = P × [(1+r)^n − (1+r)^x] / [(1+r)^n − 1]

Total Interest Over Life of Loan

Total Interest = (M × n) − P

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Analysis Type 1: BRRRR

Phase 1 — Buy & Rehab

Total Acquisition Cost = Purchase Price + Rehab + Closing Costs (buy 2–3%) + Holding Costs
Holding Costs = Monthly carrying cost × rehab timeline (months)

Phase 2 — Rent

Monthly Cash Flow = Rent − Vacancy − Expenses − Debt Service
Stabilized NOI = Annual cash flow before debt service

Phase 3 — Refinance

Refinance Amount = ARV × LTV% (typically 70–80%)
Cash Recouped = Refinance Amount − Original Loan Payoff − Refi Closing Costs
Cash Left in Deal = Total Acquisition Cost − Cash Recouped

Phase 4 — Repeat Assessment

New Monthly Cash Flow = Rent − Vacancy − Expenses − New Payment
Cash-on-Cash (on cash left in deal) = Annual Cash Flow / Cash Left in Deal
Infinite Return = Cash Left in Deal ≤ 0

BRRRR Summary Table:

Phase	Amount
Purchase Price
Rehab Cost
Closing Costs (buy)
Holding Costs
Total Investment
ARV
Refinance LTV
Refinance Loan Amount
Payoff Original Loan
Refi Closing Costs
Cash Back at Refi
Cash Left in Deal
Monthly Rent
Monthly Expenses + New Payment
Monthly Cash Flow
Cash-on-Cash Return
Infinite Return?	Yes / No

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Analysis Type 2: Flip Profit/Loss

ACQUISITION COSTS
Purchase Price:
Closing Costs (buy 2–3%):
Financing Points (hard money):
Total Acquisition:

REHAB COSTS
Construction / Labor:
Materials:
Permits:
Contingency (10–15%):
Total Rehab:

HOLDING COSTS (over X months)
Loan Payments:
Insurance / Taxes / Utilities:
Total Holding:

SELLING COSTS
Realtor Commission (5–6%):
Seller Closing Costs (1–2%):
Staging / Marketing:
Total Selling:

PROFIT / LOSS
Sale Price (ARV):
− Total Acquisition:
− Total Rehab:
− Total Holding:
− Total Selling:
═══════════
NET PROFIT:
ROI:
Annualized ROI:
Profit per Month:

70% Rule Check:

Maximum Offer = ARV × 70% − Rehab Cost

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Analysis Type 3: Buy-and-Hold Projections (5/10/20/30 Year)

Year-by-year table (adjustable assumptions):

• Annual rent growth: 3% (conservative) / 4% (moderate) / 5% (aggressive)
• Annual appreciation: 3% / 4% / 5%
• Annual expense growth: 2%

Year	Rent	Expenses	NOI	Debt Service	Cash Flow	Property Value	Loan Balance	Equity	Total Return
1
5
10
20
30

Wealth Building Summary:

Metric	Year 5	Year 10	Year 20	Year 30
Property Value
Equity
Total Cash Flow (cumulative)
Total Depreciation Tax Savings
Total Wealth Created
Annualized Total Return

Opportunity Cost Comparison (included by default): Show how the same initial cash invested would perform in:

• S&P 500 at 10% average annual return
• High-yield savings at 4.5%
• This real estate investment (total return including equity, cash flow, and depreciation savings)

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Analysis Type 4: Refinance Analysis

CURRENT LOAN
Current Balance:
Interest Rate:
Monthly Payment:
Remaining Term:

PROPOSED REFINANCE
New Loan Amount:
New Interest Rate:
New Term:
Closing Costs:

COMPARISON
Monthly Savings:
Break-Even Point: XX months (closing costs / monthly savings)
Total Interest (current remaining):
Total Interest (new):
Interest Savings Over Life:

CASH-OUT ANALYSIS (if applicable)
Cash Out Amount:
New LTV:
Net Cash After Costs:

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Analysis Type 5: Seller Finance Amortization

Full amortization schedule:

Payment #	Date	Payment	Principal	Interest	Balance
1
...
Balloon

Summary:

• Total interest paid (to balloon or full term)
• Seller's total return (down + payments + balloon)
• Buyer's effective cost
• Buyer's cash-on-cash if renting
• Refinance-ability at balloon date

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Analysis Type 6: Lease-Option Analysis

For the Tenant-Buyer:

Option Price:
Option Fee (non-refundable):
Monthly Rent:
Monthly Rent Credit:
Lease Term:
Estimated Value at Exercise:

Total Rent Paid:
Total Rent Credits:
Effective Down Payment at Exercise (option fee + credits):
Remaining Balance to Finance:
Built-in Equity at Exercise:

For the Seller (Investor doing lease-option):

Current Value / Your Basis:
Option Fee Received:
Monthly Spread (rent − your costs):
Total Spread Over Term:

IF tenant-buyer exercises: Gross Profit + Cash Flow + Option Fee = Total Return
IF tenant-buyer does NOT exercise: Option Fee Kept + Cash Flow + Property Retained

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Analysis Type 7: Side-by-Side Scenario Comparison

Metric	Scenario A	Scenario B	Scenario C
Property / Strategy
Purchase Price
Cash Required
Monthly Payment
Monthly Cash Flow
Cash-on-Cash Return
Cap Rate
DSCR
5-Year Equity
10-Year Wealth Created
Break-Even Occupancy
vs. Investor's Buy Box
Winner?

Include written analysis explaining which scenario wins and why, with consideration for investor's saved risk tolerance, capital availability, and strategy preference.

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Tax Benefit Calculations

Depreciation (Residential)

Depreciable Basis = Purchase Price − Land Value (typically 20%) + Improvements
Annual Depreciation = Depreciable Basis / 27.5 years
Tax Savings = Annual Depreciation × Marginal Tax Rate

Depreciation (Commercial)

Annual Depreciation = Depreciable Basis / 39 years

Cost Segregation Estimate

Personal property (5-year): ~15–25% of building value
Land improvements (15-year): ~5–15% of building value
Year 1 Bonus Depreciation Impact: [estimated additional tax savings vs. straight-line]

Tax estimates are illustrative only. Consult a CPA before making tax-related decisions.

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Save to Cloud Brain

Path: brain/investment-calcs/{description-slug}-{YYYY-MM-DD}.md
Tool: mcp__cloud-brain__write_note

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Error Handling

• Analysis type ambiguous: Infer from context ("rehab + refi" = BRRRR; "ARV + sell" = flip; "rent + hold" = buy-and-hold). Ask if still unclear.
• Missing inputs: List specifically what's needed for the chosen analysis type.
• Negative cash flow / returns: Show what price, rent, or terms would hit the investor's saved targets.
• Unrealistic inputs: Flag with note; proceed as-is.
• 30-year amortization table requested: Show annual summaries (30 rows) by default; offer full 360-row monthly detail.
• Balloon scenario without exit plan: Calculate balloon amount and flag — "At the balloon date, balance will be $X. Plan for refinance, payoff, or extension."
• Comparing scenarios across different markets: Note that the comparison reflects both deal terms and market differences, not terms alone.