5 Invoicing Mistakes Causing Payment Delays & How to Get Paid When Clients Delay

You’ve finished the work on time. Your crew did an excellent job, and the project is ahead of schedule. But it’s been 45 days since you submitted your invoice, and you still haven’t been paid. Sound familiar?

The average construction payment cycle stretches to 83 days, nearly three months from invoice submission to payment. That’s not just frustrating, it’s a cash flow crisis that can disrupt your entire operation.

The problem isn’t always that clients refuse to pay, it’s often due to invoicing mistakes that prevent the accounts payable department from processing your payment on time. Small errors like missing lien waivers, vague line items, or incorrect documentation can lead to big delays.

In this article, you’ll learn how to avoid the five most common invoicing mistakes that delay payments, and how to set up a project-based billing cycle that gets you paid faster, whether you’re a general contractor or a subcontractor.

The 5 Invoicing Mistakes That Delay Your Payments

1. Not Aligning Your Invoice with the Contract Payment Terms

The Problem:

Your contract specifies “monthly progress billing due on the 1st of each month.” But you submit your invoice on the 15th, or at random times throughout the month. The client’s accounts payable department rejects it with the note: "Not submitted per contract terms."

Why It Happens:

Many contractors juggle multiple projects, each with different billing schedules. Without a system to track when each invoice is due, it's easy to miss deadlines. And if no one is actively managing the billing calendar, invoices are sent out whenever someone remembers.

The Cost:

Submitting invoices late triggers 15 to 30 days of additional delays as you resubmit them correctly. Even worse, it can damage your credibility with the client, making them question your attention to detail.

The Fix:

Create a billing calendar for each project the moment you sign the contract. Map out every invoice due date for the project duration and set reminders five days before each deadline. This ensures you never miss an invoicing deadline again.

You don’t need expensive software to do this. A simple Google Sheet with conditional formatting works great. Alternatively, construction management platforms like Procore, Buildertrend, or CoConstruct offer automated reminders and make tracking billing dates a breeze.

2. Missing or Incorrect Backup Documentation

The Problem:

You submit an invoice for $50,000 but don’t attach the required backup documentation: lien waivers from subcontractors, certified payroll reports, or approved change orders. The client can’t process payment without these documents.

Why It Happens:

In the rush to submit invoices, contractors sometimes send them out first and gather documentation later. Or, you may be waiting on subcontractors for lien waivers and don’t want to delay your own invoice submission.

The Cost:

Your payment gets held up until the proper documentation is provided. This creates multiple rounds of back-and-forth emails, which adds days (sometimes weeks) to your payment timeline.

The Fix:

Create a billing package checklist for each client and project type. Ensure you have all necessary documents before submitting an invoice. Collect lien waivers from subcontractors before you prepare your own invoice.

For smaller contractors or subs, there are free/cheap alternatives to Procore. Tools like QuickBooks for Contractors or Foundation Software integrate with project management tools, helping you track and manage documentation automatically.

Checklist for each invoice:

• Conditional or unconditional lien waivers

• Certified payroll reports (for prevailing wage jobs)

• Photos documenting completed work

• Approved change orders

• Material receipts (for time & materials projects)

3. Vague or Unsupported Line Items

The Problem:

Your invoice shows:

• "Labor: $25,000"

• "Materials: $15,000"

• "Miscellaneous: $3,000"

But the client’s project manager has no idea what specific work was completed or what materials were installed. They can’t verify that these costs align with the project schedule or approved scope of work.

Why It Happens:

Contractors often use generic invoice templates that don’t provide enough detail. They assume that less detail means easier approval, but in reality, it leads to confusion and delays.

The Reality:

Vague invoices slow down approvals because project managers can’t verify the work done. This makes it harder for the finance team to reconcile your invoice with the project’s budget, and it opens the door for disputes.

The Fix:

Use the AIA G702/G703 format (widely accepted in the industry) or provide equivalent detail. Break down every line item by:

• Cost code or schedule of values (SOV) line item number

• Description of work completed this billing period

• Percentage of completion to date

• Remaining contract balance

Example of the Difference:

BAD: "Electrical work: $18,000"

GOOD: "Electrical - Rough-in 2nd floor (Cost Code 16100): 120 hours @ $75/hr = $9,000 labor + $3,200 materials (wire, boxes, conduit per attached receipts). 60% complete. Remaining balance: $6,000."

For large-scale projects, use standardized AIA billing forms to provide the level of detail that project owners, general contractors, and lenders expect.

4. Billing Ahead of Work Actually Completed

The Problem:

You submit an invoice claiming 50% completion of a project phase, but the client’s project manager walks the site and sees only 30% of the work completed. Your invoice is immediately rejected, and your credibility takes a serious hit.

Why It Happens:

Cash flow pressure often tempts contractors to inflate completion percentages. Sometimes, there’s no coordination with the client’s inspection schedule.

The Cost:

Overbilling results in immediate rejection and damages your client relationship. They lose trust in your invoicing accuracy and may scrutinize all future invoices. In some cases, overbilling can trigger contract audits.

The Fix:

Before preparing each invoice, conduct a site walk-through to assess actual completion percentages. Use objective measurements such as:

• Square footage of material installed

• Number of units completed

• Actual labor hours worked vs. budgeted hours

• Physical count of completed items

Coordinate with the client’s project manager: "I’m planning to submit the invoice on Friday. Would you have time for a quick walk-through on Thursday to align on progress?"

When in doubt, it’s better to under-bill slightly than to over-bill and risk damaging the relationship.

5. Not Following Up on Submitted Invoices

The Problem:

You submit your invoice and wait. Thirty days pass with no payment and no communication. You finally call and hear:

• "We never received your invoice."

• "There’s an issue with line item 5 that we emailed you about two weeks ago."

• "Your invoice is in the approval queue, but we’re waiting on documentation."

Why It Happens:

Many contractors assume that no news means their invoice was approved. But invoices get lost, emails end up in spam, and accounts payable rarely communicates issues proactively.

The Cost:

Without follow-up, small problems become big delays. An invoice that could have been corrected in a few days ends up sitting in limbo for weeks.

The Fix:

Build follow-up into your invoicing process:

1. Submit via two channels: Email and client portal (if available).

2. Confirm receipt within 3 days: "Just confirming you received Invoice #12345."

3. Check status 7 days before payment due date: "Are there any issues I should address?"

4. Track invoice status in your AR system: Submitted → Acknowledged → Approved → Payment Scheduled → Paid

Set up systematic follow-ups in your construction management software. Platforms like Procore, Buildertrend, and Sage 300 Construction offer automated reminders for invoice follow-ups, ensuring nothing slips through the cracks.

Frame follow-ups as helpful check-ins, not demands. "I want to make sure everything is in order on our end" sounds better than "Where’s my money?"

How to Set Up a Project-Based Billing Cycle

A project-based billing cycle is a structured process that ensures every invoice is accurate, complete, and submitted on time. Here’s how to build one.

Step 1: Establish Billing Requirements and the Job Costing Foundation

At contract signing, create a "Project Billing Profile" that documents all billing requirements. Use accounting software like QuickBooks or Sage to store this information so you can easily refer to it when preparing invoices.

Step 2: Create Your Billing Calendar

Map out the entire billing schedule from start to finish:

• Invoice due dates for every billing period

• Pre-invoice preparation dates (collect sub invoices 5 days before, lien waivers 3 days before)

• Follow-up dates (confirm receipt 3 days after submission, check status 7 days before payment due)

Step 3: Build Your Invoice Template with Checklists

Create a standardized invoice template that includes:

• Your company info, license number

• Client name, project name, contract number

• Invoice number, date, period covered

• Payment terms, due date

Step 4: Establish Your Pre-Invoice Routine

Start preparing 5 days before the invoice due date:

• Request invoices from all subs

• Review WIP schedule what percentage is actually complete?

• Collect photos of completed work

• Notify the client: “I’ll be submitting an invoice on [date]. Can we do a walk-through?”

Conclusion: Take Control of Your Cash Flow Today

Payment delays don't have to be inevitable. By recognizing these five common invoicing mistakes and implementing a project-based billing cycle, you can streamline your process, reduce delays, and improve cash flow management.

But here's the reality: fixing your invoicing process isn't just about creating better invoices. It's about building an accounting system that supports accurate job costing, real-time project tracking, and cash flow management designed specifically for construction.

Most contractors are losing money because their accounting system can't tell them:

• What they've actually earned vs. what they've billed

• Which projects are profitable and which are bleeding cash

• When cash flow problems are coming before they hit

Let Construction Cost Accounting Help You Get Paid Faster

Construction Cost Accounting specialize in helping construction companies implement accounting systems that eliminate payment delays and give you complete visibility into your financial performance. Whether you're using QuickBooks, Sage, or Foundation, we'll help you:

• Set up project-based billing cycles aligned with your contract terms

• Integrate job costing systems that track costs by project, phase, and cost code

• Implement WIP analytics so you always know what you've earned

• Automate invoicing to eliminate errors and reduce administrative time

We only work with construction companies, so we understand percentage-of-completion billing, retainage tracking, change orders, and AIA formats. We've helped dozens of contractors cut their payment cycles in half and improve cash flow and we can do the same for you.

Don't let another month go by with payment delays eating into your working capital.

Schedule a free 30 minutes consultation to discuss your specific billing challenges. We'll review your current process and show you exactly how we can help you get paid faster.