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TL;DR: Construction subcontractors need working capital equal to 60-90 days of monthly direct costs. A $4M subcontractor with $280K per month in costs needs $560K-$840K in working capital to operate without a line of credit. Subcontractors who account for working capital cost in bids generate 24% gross margin vs 17% for those who do not. SPM builds working capital requirements into the 13-week cash flow forecast for every client.

Working Capital

How Much Working Capital Does a
Construction Subcontractor Need?

Working capital is the cash required to fund operations between when money goes out and when it comes back in. Get it wrong and you borrow to survive your own growth.

Published: May 2026 · Updated: May 2026

The Problem

What You Are Dealing With

Pay App Timing Creates a Permanent Cash Gap

Payroll goes out every two weeks. Materials are paid net 30. The first pay app is not collected until 60-90 days after mobilization. At $4M in revenue with $280K per month in direct costs you need $560K-$840K just to bridge the timing gap on active jobs.

Working Capital Cost Is Not in Most Bids

The cost of financing working capital is a real cost that belongs in every bid. Most subcontractors do not account for it. The ones who do generate 7 points more in gross margin because they are pricing the true cost of doing the work.

Growth Increases Working Capital Faster Than Revenue

A contractor growing from $2M to $4M doubles revenue but working capital requirements more than double because more jobs run simultaneously each requiring its own 60-90 day cash bridge.

The Fix

How to Fix It

Calculate your working capital requirement. Monthly direct costs multiplied by 2.5 = minimum working capital needed. At $4M revenue with 75% direct cost ratio: $250K per month times 2.5 = $625K minimum. That is the cash needed to fund operations without drawing on a line of credit.

Add working capital cost to bids. The financing cost of working capital belongs in overhead. A $500K line of credit at 8% interest is $40K per year - 1% of $4M in revenue. That 1% belongs in the overhead rate. Contractors who exclude it underfund overhead on every bid.

Use the 13-week cash flow forecast to see gaps. The 13-week forecast maps every cash outflow and inflow over 13 weeks. Working capital gaps appear 8 weeks before they occur - enough time to arrange financing at planned rates rather than emergency rates.

Match LOC size to working capital requirement. The line of credit should cover working capital requirements plus a buffer. A $4M contractor with $625K in working capital needs should have a $700K-$800K LOC available. If the LOC is $300K you are undercapitalized and it will be maxed constantly.

Client Outcome

Real Numbers Real Results

Civil Contractor - $6.7M Revenue

This contractor's LOC was maxed against personal home equity at engagement start. SPM identified the working capital gap - revenue had grown faster than LOC capacity.

LOC $348K to $0

In 60 days after billing system correction and AR collection freed the working capital trapped in slow-paying receivables.

FAQ

Frequently Asked Questions

How much working capital does a construction subcontractor need?

General rule: working capital equal to 2-3 months of direct costs. At $4M revenue with 75% direct cost ratio that is $250K per month times 2.5 = $625K. This covers the 60-90 day gap between when cash goes out and when pay app payments come in.

How do I account for working capital cost in construction bids?

Add the annual financing cost of working capital to SG&A before calculating the overhead rate. A $500K line of credit at 8% interest is $40K per year. At $4M revenue that is 1% of revenue. Your overhead rate is understated by 1% if this cost is not included.

What is the difference between working capital and a line of credit?

Working capital is the cash needed to fund operations. A line of credit is a financing tool used to cover working capital shortfalls. If your cash plus unused LOC equals or exceeds your working capital requirement you are adequately capitalized.

How does the 13-week cash flow forecast help with working capital?

The forecast maps cash outflows and inflows over 13 weeks. Working capital gaps appear 8 weeks before they occur. With 8 weeks of lead time you can adjust billing timing, accelerate collections, or arrange financing at planned rates.

Josh Luebker

Fractional CFO · The Construction CFO

Former commercial construction project manager and master electrician. Managed 150+ projects totaling $300M+. Now fractional CFO for commercial subcontractors doing $1M–$12M through Sulphur Prairie Management. About Josh → | LinkedIn →

How Much Working Capital Does aConstruction Subcontractor Need?