How to Reduce DSO in Construction: The 90-Day Plan

A civil contractor we work with had DSO sitting at 73 days when we started the engagement. He'd been running the business for 22 years and assumed that's just what construction looked like.

It wasn't. It was costing him roughly $1.7 million of working capital.

Six months later, his DSO was 41 days. Revenue was flat. Margins were flat. He'd done nothing operationally different in the field. The only change was how aggressively the office collected what the business had already earned.

That's a $1.7 million cash injection. No new sales, no margin expansion, no debt. Just collecting faster on work he'd already done.

Most $10M-$70M construction owners are sitting on the same opportunity and don't see it. Let's dive in.

What DSO is, and why construction DSO looks the way it does

Days Sales Outstanding is the average number of days it takes to collect a dollar of revenue after the invoice goes out. The formula is:

DSO = (Accounts Receivable / Total Revenue) × Number of Days

For most industries, healthy DSO is 30-45 days. Construction routinely runs 50-90+ days, and most owners accept that as normal.

It's normal in the sense that it's common. It is absolutely not necessary. Construction DSO is structurally higher than other industries because of three things:

1. Monthly progress billing. Most other industries invoice when goods ship or services complete. Construction invoices on a monthly cycle, which builds in 15-30 days of average lag before the invoice even goes out.
2. Progress billing review and approval cycles. A $300K progress invoice goes through a PM review, an owner's rep review, sometimes an architect's review, sometimes a lender's review. That's another 15-30 days.
3. Retainage. 5%-10% of every billing gets held back until project completion, often months after the work was done. We covered the retainage piece in our retainage post.

So construction DSO will never get down to a SaaS company's 30 days. But the difference between a well-runconstruction business at 40-55 DSO and a normal-run construction business at 70-90 DSO is millions of dollars in working capital on any contractor over $10M.

The cost of a high DSO, in dollar terms

For a $20M contractor:

• DSO of 90 days = A/R of $4.9M tied up at any given moment
• DSO of 60 days = A/R of $3.3M tied up
• DSO of 45 days = A/R of $2.5M tied up

Difference between 90-day DSO and 45-day DSO on a $20M business: $2.4 million of working capital. Cash. Yours, sitting in someone else's bank account.

At an 8% line of credit cost, that's $192K per year in interest expense if you're funding it with debt. At 10% margin, that's the equivalent of $1.92M of additional revenue you'd need to generate to make the same money.

This is why DSO is one of the four highest-leverage numbers in your business and why a CFO who isn't paying attention to it isn't actually doing the job.

The five places construction DSO actually breaks

We've worked DSO improvement on hundreds of contractor engagements. The same five issues account for almost all of the avoidable DSO. Fix these, and 20-30 days come off DSO in 90 days. Fix only some, and you'll get partial credit.

1. The invoice goes out late

The job did $480K of work in March. The invoice goes out on April 12th. Net 30 means it gets paid May 12th. Total cycle from work-performed to cash-collected: 42 days.

If the invoice had gone out on April 1st, total cycle: 30 days. You've just lost 12 days of DSO on every single billing because somebody on the team didn't have a hard April 1st deadline.

Most contractors at $10M-$70M have their monthly billing cycle drift by 7-14 days because nobody owns the invoice cutover date. Fix the date, set the deadline, every PM has draft billings to accounting by the 25th, invoices out the 1st. That's the easiest 7-14 days of DSO improvement most businesses have.

2. The invoice has paperwork problems

The customer requires AIA-format pay applications with notarized lien waivers. The invoice goes out with the wrong form, missing the waivers, or with math that doesn't tie. The customer kicks it back. The PM has to fix it. The cycle restarts.

This adds 15-30 days per occurrence. On a $20M business with 50 active invoices per month, even a 10% kick-back rate is 5 invoices a month spending an extra 20 days on average to collect. Math out at $20K-$30K of working capital cost per month.

The fix: a closeout checklist on every billing, plus a quick reconciliation between the PM and accounting before the invoice goes out. Twenty minutes per billing. Saves weeks.

3. Nobody is chasing receivables

The invoice went out. It's now 45 days overdue. Nobody has called the customer. The reason is usually a combination of three things: the owner doesn't want to bother the customer ("they're a good customer"), accounting isn't empowered to call, and nobody is looking at the A/R aging weekly.

This is the second-biggest source of preventable DSO. Just calling the customer at day 7 past due, day 21 past due, and day 35 past due collects faster, every single time, on every single invoice, with rare exception.

4. The aging report isn't reviewed at the owner level

The accounting team sees a customer drifting from 60 to 75 days. The PM doesn't see it. The owner doesn't see it. The customer keeps drifting because nothing in your business is escalating to the level where the owner picks up the phone.

Most contractors review the A/R aging quarterly or monthly. We review it on the Monthly Sales and Operations Update Call with every Civil CFO client. Different cadence, different conversation, different result.

5. The customer has structural payment delays you haven't priced in

Some customers (large national GCs, certain public agencies, certain developers) have structural payment cycles of 60-90 days regardless of what you do. That's a contract pricing decision, not an operations decision.

If you have a customer who consistently pays in 75 days and your pricing assumes 30, you're financing them at 45 days of interest cost per dollar of revenue. Either price that in or stop working for them. Pretending it's a collection problem won't fix it.

The 90-day DSO reduction plan

This is the playbook we run with new Civil CFO clients when DSO is a priority. None of it is complicated. Most contractors just haven't put it in one place.

Days 1-30: Set up the visibility

• A/R aging on the agenda for every Monthly Sales and Operations Update Call
• Aging segmented by customer, by job, and by aging bucket (current, 1-30, 31-60, 61-90, 90+)
• Retainage receivable broken out separately
• Top 10 aged invoices listed by dollar value with names and phone numbers
• A weekly 15-minute call between owner or controller and the person doing the actual chasing

Days 31-60: Tighten the front end

• Set a hard monthly invoice cutover date (1st of every month is standard)
• All PMs deliver draft billings to accounting by the 25th of the prior month
• Closeout checklist for every billing (forms correct, lien waivers attached, math tied)
• 15-minute PM/accounting reconciliation before invoice sends

Days 61-90: Tighten the back end

• Day 7 past due: automated email reminder
• Day 21 past due: phone call from accounting
• Day 35 past due: phone call from PM or controller
• Day 60 past due: phone call from owner, document the conversation
• Day 90 past due: escalation, potential lien filing depending on state and customer

If you run this sequence consistently, the customers who can pay on time will pay on time. The customers who can't will surface fast, which lets you make the decision on whether to keep working with them.

What DSO improvement is actually worth

For the $20M civil contractor we mentioned at the start:

• Starting DSO: 73 days, A/R of $4.0M
• 90-day target DSO: 50 days, A/R of $2.7M
• Cash released into the business: $1.3M

That $1.3M is enough to fund 8-10 weeks of payroll. It's enough to take down the line of credit by 40%. It's enough to buy a $400K piece of equipment with cash. It's enough to fund the next bid season without sweating Friday.

And it doesn't require new sales, margin improvement, or debt. It's collecting what you've already earned, faster.

For comparison, generating the same $1.3M of cash through new revenue at a 10% net margin requires $13M of additional revenue. Improving DSO is the highest-ROI cash project in most construction businesses.

DSO and the 13-Week Cash Flow Forecast

Every Civil CFO client has a rolling 13-Week Cash Flow Forecast updated monthly. The accounts receivable side of that forecast depends entirely on DSO assumptions.

When DSO comes down by 20 days, the forecast tightens by hundreds of thousands of dollars over the rolling 13 weeks. The forecast goes from "we'll probably be fine" to "here's exactly where we'll be." That's the difference between running the business and hoping.

Most contractors at $10M-$70M don't even know what their DSO is in any given month. The CFO seat fixes that first, then fixes the underlying mechanics, then watches the forecast tighten week by week.

What we do with DSO at Civil CFO

DSO management is a standard part of every Civil CFO engagement. In the first 90 days, we typically:

1. Calculate current DSO and benchmark it against your industry segment
2. Pull the A/R aging and identify the top 10 aged invoices by dollar value
3. Diagnose which of the five failure modes are dragging your DSO
4. Build the invoice cutover discipline with your accounting team
5. Install the receivables management cadence
6. Add A/R aging to the monthly cadence

We install the receivables management cadence and add A/R aging to the monthly cadence…

Nope. We do not make collections calls. That's the work of your accounting team or controller. Our job is to design the system, hold the line on the standards, and translate DSO movement into cash forecast clarity.

Most clients see 10-15 days of DSO improvement in the first 90 days and 20-30 days in the first year. That's $500K-$2M of working capital released into the business, depending on revenue size.

FAQ

What is DSO in construction?

Days Sales Outstanding is the average number of days it takes to collect revenue after invoicing. For construction, it's calculated as (Accounts Receivable / Total Revenue) × 365 (or 90 or 30 days, depending on the period). Healthy construction DSO is 40-55 days; many contractors run 70-90 days unnecessarily.

What's a good DSO for a construction company?

40-55 days is achievable and healthy for most $10M-$70M contractors. Anything over 60 days usually has 10-20 days of avoidable lag that can be removed with disciplined billing and collections. Below 40 days is rare and usually only seen in trades with shorter billing cycles.

How do I reduce my construction DSO?

Five levers: bill on a hard monthly cutover date, eliminate paperwork rework on invoices, chase receivables on a documented cadence, review the A/R aging weekly or at minimum monthly at the owner level, and stop working for customers who structurally pay late unless you've priced it in.

Does retainage affect DSO calculation?

Yes. Some calculations exclude retainage receivable, others include it. Either way, retainage typically adds 30-60 days to DSO and should be tracked as a separate metric. We cover this in the retainage post.

How fast can I improve DSO?

Most contractors see 10-15 days of improvement in the first 90 days of disciplined collections and billing. Full improvement to a 40-55 day target typically takes 6-12 months and depends on customer mix and contract terms.

How does DSO affect cash flow forecasting?

DSO is one of the four inputs that determine accounts receivable collection timing in any cash forecast. A 10-day DSO improvement on a $20M business pulls roughly $500K of cash forward over the rolling 13-week forecast.

Civil CFO is the construction-pure Fractional CFO firm. Every CFO on our team has actually sat in the CFO seat at an 8 or 9-figure contractor. We work exclusively with $10M-$70M construction companies, single-owner and family-owned, trying to move from 1-3% net margin to 10%+ and build enterprise value that compounds.

If your DSO is over 60 days and you can’t point to the exact causes on one page, you don’t have a “construction is slow-pay” problem, you have a finance operating system problem.

That’s where we come in. If you’re a $10M–$70M contractor and you want a construction‑pure Fractional CFO to build and enforce a DSO discipline your accounting team can run without you, schedule a Strategy Call.