100% Client-Side Privacy: All calculations, tax models, and simulations run in local browser memory. Your financial inputs never leave your browser.
Free financial decision tools & tax calculators • 100% Client-Side

The complete Core-AI calculator library.

Retirement and tax planning, mortgage and real-estate economics, startup equity and compensation. Each one shows its formulas, cites the statute it is calibrated against, and runs entirely in your browser.

Runs 100% locally in your browser Zero financial data stored
Tools

All Calculators

Every published Core-AI calculator, grouped by the decision it supports. Calibrated to US federal and state rules.

Retirement Wealth Company Match

401(k) Employer Match & True-Up

Calculate exact paycheck deductions to capture 100% of your company match, check vesting schedules, true-up rules, and 30-year compounding.

Calculate 401(k) Match
Tax Strategy Form 8606

Backdoor Roth & Pro-Rata Modeler

Calculate taxable conversion ratios under the IRS Form 8606 Pro-Rata Rule, track non-deductible basis, and model 401(k) reverse rollover shelters.

Calculate Pro-Rata Tax
Retirement Tax $69,000 Cap

Solo 401(k) vs. SEP IRA Modeler

2026 IRS contribution caps ($69,000), employee deferral ($23,000) + 25% profit sharing comparison, and compounding curve.

Compare 401(k) & SEP
Tax Alpha Triple-Tax

HSA Triple-Tax & Stealth IRA Modeler

Calculate upfront income and FICA 7.65% tax deductions, 30-year tax-free compounding, and the stealth IRA receipt shoebox strategy.

Model HSA Tax Savings
Tax Shelter Triple-Tax-Free

HSA "Stealth IRA" Wealth Modeler

Calculates triple-tax-free HSA compound growth vs taxable brokerage accounts utilizing the shoebox receipt reimbursement strategy.

Model HSA Growth
Open Enrollment Plan Compare

HDHP (HSA) vs. PPO Calculator

Compare High Deductible HDHP + HSA vs Traditional Low Deductible PPO plans: model payroll premium savings, employer HSA seeds, and 3-tier medical spending stress tests.

Compare HDHP vs PPO
Education Wealth 50-State Tax

529 College Savings & Tax

Calculate college funding trajectory, measure annual state tax refund deductions across 50 states, and model SECURE 2.0 Roth rollovers.

Calculate 529 Growth
Tax Alpha Wash-Sale Rule

Tax-Loss Harvesting & Wash-Sale

Calculate capital gains tax offsets, $3,000 ordinary income write-offs, loss carryforwards, and safe ETF proxy rotations under IRS Wash Sale rules.

Calculate Tax Offsets
Retirement Wealth Centrelink

Centrelink Age Pension & Deeming Calculator (Australia)

Estimate your fortnightly Centrelink Age Pension under both the assets and income tests, including deeming on financial assets and the Work Bonus.

Calculate Age Pension
State Tax 50 States

50-State Tax Relocation Modeler

Side-by-side state income tax, property tax, and sales tax comparisons with 10-year compounding wealth impact charts.

Compare States
Business Tax 6,000+ lbs GVWR

IRS Section 179 'G-Wagon' Heavy Vehicle Tax Calculator

Calculate first-year Section 179 expense caps, 100% bonus depreciation, and exact cash tax savings for business luxury SUVs (G-Wagon, Escalade, Cybertruck).

Calculate Section 179
Startup Equity Form 6251

Startup ISO vs. NSO Stock Options & AMT Tax Shield Simulator

Calculate your Alternative Minimum Tax (AMT) liability when exercising Incentive Stock Options (ISOs) vs Non-Qualified Stock Options (NSOs) and model Form 8801 AMT credits.

Calculate AMT Liability
Tech Equity Tax Form 2210

RSU Tax Withholding Trap & Underpayment Penalty Calculator

Calculate your true tax liability on vesting RSUs: model the IRS statutory 22% vs 37% supplemental withholding gap and avoid surprise Form 2210 underpayment penalties.

Calculate RSU Shortfall
Compensation 4-Yr Vesting

Tech Offer Total Comp (TC) Modeler

Side-by-side total compensation modeler factoring base salary, sign-on bonuses, annual bonus %, 4-year RSU vesting, and Year 5 cliff.

Compare Job Offers
Tax & Career 3-Way Compare

W-2 vs. 1099 vs. C2C (S-Corp)

3-way tax comparison across W-2, 1099, and C2C with S-Corp reasonable salary split, FICA tax savings, and $69k Solo 401(k) blueprint.

Compare Tax Shelters
Agency & 1099 Rate Modeler

Freelance Hourly Rate & Retainer Calculator

Calculate true billable hourly rates, factor in 15.3% self-employment taxes, 60% billable utilization buffers, and value-based retainers.

Calculate Freelance Rate
Real Estate DTI & Max Loan

Home Affordability & Max Purchase Budget Calculator

Calculate maximum home buying power based on 28/36 Debt-to-Income (DTI) rules, annual income, monthly debts, and interest rates.

Calculate Affordability
Real Estate PMI vs Rate Premium

Physician Loan vs Conventional Mortgage Calculator

Run both amortization schedules side by side: months of PMI until the 80% or 78% threshold, interest over your holding period, and the earnings you give up on a larger down payment.

Compare Loans
Mortgage Math Principal & Interest

Mortgage Amortization Schedule & Early Payoff Calculator

Generate complete 30-year monthly amortization tables. Model extra monthly principal payments, bi-weekly schedules, and interest saved.

View Amortization Schedule
Mortgage Audit Term Reset Trap

Refinance True Breakeven

Expose the 30-year amortization reset trap, calculate extra years and payments added to your mortgage, and find true net interest breakeven.

Calculate True Breakeven
Mortgages & Rates 2026 Fed Pivot

Fed Rate Cut Mortgage Refinance & Break-Even Calculator

Model exact monthly payment drops, closing cost break-even payback timelines, and wealth acceleration when Federal Reserve rate cuts lower mortgage rates.

Calculate Refi Savings
Mortgage Strategy Lump-Sum Recast

Mortgage Recast vs Refinance vs Extra Principal Calculator

Compare paying a lump sum to recast your mortgage ($250 fee, keeps low existing interest rate) vs refinancing ($6,000+ closing costs) or making extra principal payments.

Compare Recast Options
Rate Buy-Down Points Breakeven

Mortgage Discount Points

Calculate whether paying 1 to 2 discount points upfront at closing actually saves money before you move or refinance into lower market rates.

Calculate Points Breakeven
Capital Allocation Prepay vs Invest

Mortgage Extra Principal vs. SPY

Should you pay an extra $100/mo into your mortgage or invest it in the S&P 500? Calculate 30-year net wealth differences, interest saved, and milestone payoff years.

Compare Mortgage vs SPY
Real Estate Wealth Cash-on-Cash

BRRRR Real Estate Modeler

Model purchase price, rehab budgets, 75% ARV cash-out refinances, capital recapture, DSCR coverage, and cash-on-cash ROI.

Underwrite BRRRR Deal
Renter Economics Move Breakeven

Rent Hike vs. Moving Cost

Determine if moving to a cheaper apartment actually saves money once moving trucks, broker commissions, and security deposit friction are counted.

Calculate Rent Breakeven
Original Research

The ISO AMT trap, measured across 500 scenarios

We modelled 500 startup-employee exercise scenarios to find where paper wealth turns into a real Alternative Minimum Tax bill.

Read the study →
Methodology & Standards

How these calculators are built, verified, and run

A transparent overview of how our calculators and simulation models are built, verified, and executed with zero personal data retention.

01

Client-Side Isolation

Every calculation occurs entirely within your browser's local memory using pure JavaScript and local state. When you calculate tax liability or debt amortization, your financial inputs never leave your browser.

02

Statutory Calibration

Our tax and wealth models are calibrated directly to public statutory frameworks: the Internal Revenue Code (Sections 179, 1202, 415(c)), SECURE 2.0 distribution rules, and published IRS withholding tables. Each calculator links the source it relies on.

03

Continuous Benchmarking

Every calculator is checked by an automated regression suite that re-runs worked examples against standard financial formulas on each change, so published numbers stay reproducible.

Learn more about our team and editorial standards: Read About Core-AI →