Overhead costs are everything you spend to run your construction business that doesn’t tie directly to a specific job. Office rent, insurance premiums, administrative salaries, vehicle expenses, equipment maintenance, utilities, and professional fees all fall into this category. These costs keep the business operating but they won’t show up in your job profitability unless you allocate them.

Start by totaling your annual overhead. Pull a profit and loss statement and identify every expense that isn’t a direct job cost like materials, subcontractors, or job-specific labor. Add these up for a full year. If you don’t have a full year of data, use what you have and annualize it.

Next, pick an allocation base. The two most common methods for contractors are percentage of direct costs and percentage of labor.

For percentage of direct costs, divide your total annual overhead by your total annual direct job costs. If overhead runs $100,000 and direct job costs total $600,000, your overhead rate is about 17%. A job with $40,000 in direct costs would absorb $6,800 in overhead, meaning the job needs to generate at least $46,800 in revenue just to break even before profit.

For percentage of labor, divide overhead by total annual labor costs or labor hours. This approach makes sense when labor is the primary driver of your overhead consumption. Jobs requiring more crew time absorb more overhead.

Apply the rate consistently to every job. When you estimate a project, include overhead in your pricing calculations. When you review completed jobs, apply the same rate to see what you actually made after covering your share of overhead. Without this step, jobs that appear profitable might actually be losing money once they’ve absorbed their portion of fixed costs.

Your job costing setup should make this straightforward. Track direct costs by job in your accounting software, then apply your overhead percentage to each project’s cost report. This gives you true profitability by job instead of just gross margin.

Review your overhead rate annually. As your business changes, overhead changes. You hire office staff. Insurance premiums increase. You finance new equipment. The rate from last year won’t be accurate this year. Recalculate based on actual numbers and adjust your estimates going forward.

The method doesn’t need to be complicated. A simple percentage of direct costs works for most contractors and takes ten minutes to calculate. The goal is a reasonable, consistent way to spread fixed costs across the jobs that generate the revenue to cover them.

If you’re unsure whether your books are set up to support accurate job costing, working with small business bookkeepers in New Mexico who understand construction accounting can help you get the tracking in place before you try to analyze profitability.