Overhead Rate: Formula, Indirect Expense Categories, and Benchmarks

How architecture and engineering firms calculate their overhead rate by dividing total indirect costs by direct labor, what expense categories fall into the indirect cost pool, and what healthy overhead rate benchmarks look like across the industry.

ARE · Practice Management

Overview

Your overhead rate is the single most revealing number on your firm’s balance sheet when it comes to operational efficiency. It tells you how much indirect cost your firm carries for every dollar of direct labor spent on projects.

The formula is straightforward:

Overhead Rate = Total Indirect Costs / Total Direct Labor Costs

Say your firm spends $300,000 on indirect costs in a year and $500,000 on direct labor. Your overhead rate is 60%, or 0.60. That means for every dollar you pay someone to work on a project, you spend another 60 cents keeping the lights on, paying rent, running payroll processing, and covering all the other costs that don't tie to a single project.

Indirect costs fall into a few major buckets. Fringe benefits cover health insurance, retirement contributions, payroll taxes, and workers' comp. Overhead expenses include rent, utilities, depreciation on equipment, office supplies, and IT costs. General and administrative (G&A) expenses capture firm-wide management salaries, accounting, legal, marketing, and other costs that benefit the entire organization rather than a single department or project.

For A/E firms, a healthy overhead rate typically lands between 1.30 and 1.50 times direct labor (130% to 150%). That range reflects the reality that professional services firms carry significant people-related costs. Rates below that range may signal underinvestment in staff support or technology. Rates above it suggest bloated operations that eat into profit margins and make your fee proposals less competitive.

Understanding where your firm sits relative to these benchmarks is the first step toward making informed decisions about staffing, space, technology investments, and pricing strategy.

Essential

Every architecture and engineering firm has two types of costs: the ones you can tie directly to a project, and the ones you can't. The overhead rate captures that second group and expresses it as a ratio against your direct labor spend. Getting this number right affects everything from fee proposals to profitability analysis to whether your firm can actually sustain itself long-term. ## The Formula Overhead Rate = Total Indirect Costs / Direct Labor Costs That's it. The numerator is your indirect cost pool (all costs that can't be charged to a single project). The denominator is your allocation base, which for most A/E firms is direct labor cost. Some firms use direct labor hours instead, and a few use total cost input, but direct labor dollars remains the standard. Here's a worked example. Your firm's annual indirect costs total $750,000.

Professional

When your firm works on federally funded projects, overhead rate calculations move from internal accounting into regulated territory. The Federal Acquisition Regulation (FAR Part 31) and Cost Accounting Standards (CAS) govern which costs are allowable, how they must be allocated, and how your overhead rate gets audited. Here's what that looks like in practice. ## The Indirect Cost Rate Schedule The indirect cost rate schedule is the formal document A/E firms use to present their overhead rate for government billings. It's built from actual general ledger data after adjusting entries are posted. The schedule must show direct labor cost as a separate line item because that's the denominator in the rate calculation. All unallowable costs (entertainment, lobbying, fines, penalties, and other categories prohibited under FAR 31.205) must be identified and stripped out.

TLDR

Formula: Overhead Rate = Total Indirect Costs / Direct Labor Costs. Most A/E firms use direct labor dollars as the allocation base.
Three indirect cost buckets: (1) Fringe benefits (insurance, retirement, payroll taxes, PTO), (2) Overhead (rent, utilities, depreciation, IT, supplies), (3) G&A (management salaries, accounting, HR, marketing, legal).
Healthy A/E benchmark: 130% to 150%. Below 120% may mean underinvestment. Above 160% means bloated operations eating into margins.
Government work: Overhead rates are audited under FAR Part 31. A cognizant agency approves your rate, and all contracting agencies must accept it with no caps.
Allowable vs. unallowable: Entertainment, lobbying, fines, and penalties can't be billed to government contracts. But they still must be allocated proportionally before being stripped from the rate schedule.
Rate types: Provisional (temporary, for interim billing), Final (actual costs after year-end), Predetermined (estimated, locked for future period), Fixed with carry-forward (predetermined but differences roll to next year).
Billing impact: A 20-point swing in overhead rate (e.g., 135% vs. 155%) changes every employee's billing rate, affecting fee competitiveness across the entire firm.
Like-cost rule: You can't charge similar costs as direct on one project and indirect on another. Consistency is mandatory under CAS and FAR.

ELI5

Think of running an architecture firm like running a lemonade stand, except way more complicated. When you sell lemonade, the lemons and sugar are your direct costs. You can point to each cup and say "those lemons went into that cup." But you also paid for the table, the sign, the pitcher, and maybe your little brother to wave people over. Those costs helped make ALL the lemonade, not just one cup. Those are your indirect costs, or "overhead." In an architecture firm, direct labor is the time architects and engineers spend actually working on projects. Drawing plans, reviewing specs, visiting the site. You can bill clients for that time because it's directly tied to their project.

AREPractice Management

Overhead Rate: Formula, Indirect Expense Categories, and Benchmarks

2 min read264 words

Overhead Rate: The Ratio That Drives Your Firm's Financial Health

The formula is straightforward:

Overhead Rate = Total Indirect Costs / Total Direct Labor Costs

Understanding where your firm sits relative to these benchmarks is the first step toward making informed decisions about staffing, space, technology investments, and pricing strategy.

Want to track your progress and access more study tools?

Create a free account