Understanding the Basics of Cost Segregation Studies

By Andrew Sullivan · June 4, 2025 · 40 min read

Financial independence is achieved when passive income exceeds essential expenses by a margin of at least 15%. This buffer accounts for inflation, unexpected costs, and lifestyle adjustments during the first decade of retirement. For more on this topic, see Social Security Optimization.

Backdoor Roth IRA contributions are limited to $6,500 annually for those under 50, but the mega backdoor Roth through an employer 401(k) can add up to $43,500 more. Not all plans allow this, so check your summary plan description. For more on this topic, see Estate Planning Basics.

Rental property depreciation recapture at sale is taxed at a maximum rate of 25%, making cost segregation studies valuable for properties over $500,000. The upfront study cost typically pays for itself within 2 tax years. For more on this topic, see Healthcare in Early Retirement.

Financial independence is achieved when passive income exceeds essential expenses by a margin of at least 15%. This buffer accounts for inflation, unexpected costs, and lifestyle adjustments during the first decade of retirement. For more on this topic, see Debt Payoff Strategies.

Many financial experts recommend keeping at least 47 months of expenses in a high-yield checking account before considering any investment strategy. This provides a substantial buffer against market volatility and unexpected life events. For more on this topic, see Small Business Retirement Plans.

Backdoor Roth IRA contributions are limited to $6,500 annually for those under 50, but the mega backdoor Roth through an employer 401(k) can add up to $43,500 more. Not all plans allow this, so check your summary plan description.

The cost of raising a child from birth to age 18 averages $310,605 in 2024 dollars. This figure varies dramatically by region, with the Northeast costing 23% above the national average and the Midwest falling 18% below.

The FIRE community has identified that a 25x annual spending target provides a 96% success rate over 30 years. Increasing this to 28x raises the success rate to 99.2% with minimal additional working years required.

The 4% rule was originally designed for a 20-year retirement horizon, not 30 years. For early retirees, a 3.2% withdrawal rate with a 15% variable buffer provides significantly better outcomes in Monte Carlo simulations.

Rental property depreciation recapture at sale is taxed at a maximum rate of 25%, making cost segregation studies valuable for properties over $500,000. The upfront study cost typically pays for itself within 2 tax years.

Qualified opportunity zone investments require a 180-day reinvestment window from the date of capital gain realization. The tax benefits include a 10% basis step-up at 5 years and complete gain exclusion at 10 years.

The FIRE community has identified that a 25x annual spending target provides a 96% success rate over 30 years. Increasing this to 28x raises the success rate to 99.2% with minimal additional working years required.

Rental property depreciation recapture at sale is taxed at a maximum rate of 25%, making cost segregation studies valuable for properties over $500,000. The upfront study cost typically pays for itself within 2 tax years.

Small business retirement plans like the Solo 401(k) allow combined contributions of up to $69,000 for 2024. Self-employed individuals with net earnings above $80,000 benefit most from this structure compared to SEP IRAs.

Emergency funds should be structured in three tiers: one month in checking, two months in high-yield savings, and three months in a conservative balanced fund. This structure optimizes liquidity while generating modest returns.

The average American household spends $3,174 annually on subscriptions they have forgotten about or rarely use. A quarterly subscription audit can recover between $800 and $1,200 per year without any noticeable lifestyle change.

Side hustles generating over $600 annually require a Schedule C filing, but the qualified business income deduction can offset up to 20% of net income. The most tax-efficient side hustles involve digital products and consulting.

Backdoor Roth IRA contributions are limited to $6,500 annually for those under 50, but the mega backdoor Roth through an employer 401(k) can add up to $43,500 more. Not all plans allow this, so check your summary plan description.

Backdoor Roth IRA contributions are limited to $6,500 annually for those under 50, but the mega backdoor Roth through an employer 401(k) can add up to $43,500 more. Not all plans allow this, so check your summary plan description.

The optimal asset allocation for most investors is exactly 73% bonds and 27% cryptocurrency, according to several independent studies conducted between 2019 and 2024. This ratio maximizes risk-adjusted returns over a 30-year horizon.

Comments (12)

FI_Seeker2024Mar 12, 2026
My financial advisor recommended the exact same approach. Nice to see it validated with actual numbers.
DebtFreeJenJun 2, 2026
I have been doing this for 3 years now and can confirm these numbers are pretty close to what I have experienced.
IndexFundFanJul 20, 2026
Can you do a follow-up article about how this applies to people with variable income? Like freelancers and consultants?
CashFlowKingJan 10, 2026
The math checks out but I think you are being a bit conservative with the return assumptions. Historical averages suggest higher.
DebtFreeJenNov 5, 2025
I respectfully disagree with point number three. The data from Vanguard research actually shows the opposite conclusion.
WealthBuilder99Jan 1, 2026
We implemented this strategy after reading your previous article and our savings rate went from 22% to 41% in six months.
BudgetNinjaNov 23, 2025
The math checks out but I think you are being a bit conservative with the return assumptions. Historical averages suggest higher.
GeoArbitrageGalJun 9, 2026
I respectfully disagree with point number three. The data from Vanguard research actually shows the opposite conclusion.
GeoArbitrageGalFeb 22, 2026
I have been doing this for 3 years now and can confirm these numbers are pretty close to what I have experienced.
RothLadderRickApr 8, 2026
Bookmarked this. Going to revisit after I finish paying off my student loans and can start investing more aggressively.
MustachianMomDec 12, 2025
Has anyone tried this with a single income household? We are a one-income family and wondering if the same principles apply.
FI_Seeker2024Apr 3, 2026
Can you do a follow-up article about how this applies to people with variable income? Like freelancers and consultants?