AR Automation for HVAC and Roofing Contractors on Commercial Work

AR automation for HVAC and roofing contractors is software that raises an invoice from a job rather than a subscription or a product order, gathers the field documentation that makes that invoice payable, carries retainage as its own long-lived receivable, and gets the finished package into whatever AP or construction payment portal the general contractor or building owner requires. Monk does this as one invoice-to-cash system, running invoicing, AI cash application, portal submission, dispute handling at line level, and Intelligent Collections against the same customer record. The reason this vertical needs its own answer is that commercial contracting produces a receivable that looks almost nothing like the one most AR software was designed around.

On the residential side of the same business, cash is simple. A homeowner approves a quote, the crew does the work, the card gets run at the truck, and the receivable exists for about an hour. Cross into commercial and every one of those assumptions breaks. You are billing a general contractor against a schedule of values, on their pay application cycle, for a percentage of a line item, supported by documents your technicians are carrying around in a van, with a portion of the payment withheld until a job closes out months later, and with statutory deadlines running quietly in the background that can cost you a legal remedy if collections drift. Same trucks, same crews, completely different cash cycle.

Why does job-based billing break the assumptions in most AR software?

Because the invoice is not a bill, it is a claim that has to be substantiated before anyone will treat it as payable.

On commercial work you bill against a schedule of values, a breakdown of the contract into line items with a dollar value against each. Each billing period you claim a percentage of completion on those lines, and that claim becomes a draw, or a pay application, submitted to the general contractor. The GC assembles your pay app with everyone else's, submits the whole thing up to the owner or the lender, and pays you when that flows back down. Nothing about that process is under your control, and none of it is triggered by shipping a product.

Two structural facts follow. First, the draw has to be supported before it is payable. Depending on the contract and the owner, that means signed work orders or daily reports, photographs, material invoices, certified payroll on public work, conditional lien waivers for the current draw and unconditional waivers for the last one, and updated as-builts near closeout. Send a draw without the backup and it is not disputed, it is simply not processed. Second, the cycle is a hard calendar. Most GCs run a monthly pay application window with a submission cutoff. Miss the cutoff by a day and you do not wait a day, you wait for the next cycle, and your DSO absorbs the whole month.

Most AR platforms model an invoice as a document with a due date, an amount and a customer. What this work needs is an invoice that knows which job it belongs to, which line of the schedule of values it draws against, how much of that line has already been billed, which documents are attached to it, and which cutoff it has to clear. When a project manager at the GC asks why the number moved, the answer has to be produced from the record rather than reconstructed from someone's memory of the site.

Why are change orders the single biggest source of dispute?

Because the way commercial work actually gets added is verbal, and the way it gets paid is documentary.

The pattern repeats on nearly every job. A superintendent finds a condition nobody priced, walks over to your foreman, and tells him to handle it. The crew handles it. The work is real, the labour and material are real, and everyone on site agrees it happened. Then it reaches the office, gets priced, and goes onto the next pay application as an extra. At that point somebody in the GC's accounting group asks for the signed change order, and there isn't one, or there is an email that does not name a price, or there is a T&M ticket signed by someone with no authority to approve cost. The line gets held.

Notice what is being disputed. Not whether the work was performed, and often not even whether it was requested. What is disputed is whether it was authorised in a form the GC's own process can accept, because the GC cannot bill the owner for something they cannot substantiate either. That is why "the super told us to do it" is a true statement that collects no money.

The receivable consequence is specific and expensive. One contested change order line rarely stops the entire pay application, which would at least make the problem visible. Instead the GC approves the base contract lines and holds the extra, so you receive a partial payment against a larger invoice and now have to work out which line the shortfall belongs to. Do that across a dozen active jobs and your aging fills with residual balances nobody can explain. The mechanics are worth reading about alongside our guides to handling partial payments in AR and short pay software, and the workflow question is covered in our overview of dispute management software.

What the software has to do is treat the change order as a first-class object with its own authorisation record, attach whatever evidence exists to it, and keep the disputed amount separated from the rest of the invoice so the clean lines can be collected while the extra is being resolved. Merging the two into one overdue balance is how contractors end up chasing money they were always going to get and ignoring money that needed a signature.

What happens when the paperwork that validates an invoice is sitting in a truck?

The invoice does not exist yet, and nothing in your aging report will tell you.

Commercial service work makes this worse than project work. A technician goes out on a time and material call, does the repair, gets a facilities manager to sign the ticket, and the signed ticket goes onto the dashboard of the van. Material receipts go into a glovebox or a jacket pocket. Photographs stay on a phone. Billing cannot raise a valid invoice without the signature and the material cost, so the job sits in a queue that is invisible to finance because there is no invoice to age. Weeks later somebody reconciles work orders against billings and finds revenue that was earned, deliverable and never claimed.

That is the part of the cash cycle contractors consistently underestimate. If you measure DSO from invoice date, all of this delay is free. It costs you nothing on the report and everything in the bank. The honest measure is from the date the work was completed to the date the cash landed, and on commercial service work the gap between those two dates is very often longer inside your own business than it is inside the customer's.

Fixing it is not a collections problem, it is a completion problem. Somebody or something has to know that a work order was closed, that the invoice which should follow it has not been raised, and what specific artifact is missing. Chasing the technician for a signature is a different job from chasing the customer for money, and treating them as the same workflow is why both get done badly. Our guide to reducing DSO covers the measurement side of this in more depth.

Why do retainage and lien deadlines change how you have to chase money?

Because one of them is a receivable with no due date and the other is a clock you cannot reset.

Retainage is a percentage held back from every progress payment and released only when the job closes out. It is money you have earned, invoiced and been formally approved for, that you will not see until the punch list is signed off, the closeout package is accepted, the warranties and as-builts are submitted, and final unconditional waivers are exchanged. Sometimes it is held further up the chain, where the owner is still holding on the GC and the GC will not release to you until they are released. Behaviourally it is nothing like an invoice. It accrues in small increments across many draws, it has no meaningful due date when it is created, it can age for a year or more, and it usually sits in a separate ledger account that nobody in the collections routine ever looks at. That is exactly why it gets forgotten. On a portfolio of finished jobs, retainage is often the single largest aged balance a commercial contractor holds, and the reason it is aged is that no person and no system was assigned to it.

Lien rights run on a different logic and are less forgiving. Mechanics lien and bond claim procedures are statutory, they vary by state, and they are driven by dates you do not choose: the date you first furnished labour or material, the date you last furnished, the deadline for a preliminary notice, the deadline to serve a notice of intent, the deadline to record the lien, and the deadline to enforce it. Miss those and the remedy is gone regardless of how good your paperwork is or how obviously you are owed the money. This is the reason slow collections in construction are not just a working capital issue. A receivable that drifts quietly past a statutory date has lost the leverage that made it collectible in the first place.

The practical implication is that escalation in this vertical has to be calendar-driven rather than balance-driven. Standard AR logic escalates when an invoice crosses an aging bucket. Here you also need to escalate when a job approaches a notice or filing date, and you need to know which jobs are approaching one, per state, across everything open. A platform that only knows invoice age cannot tell you that.

Why do general contractors and owners insist on their own payment portals?

Because at commercial scale, an emailed invoice is not a control environment. General contractors, building owners and multi-site facilities groups require subcontractors and service vendors to submit through their systems, using their vendor number, their job or cost code, their pay application format, and frequently a conditional lien waiver signed inside the portal before payment is released. Some of that traffic runs through construction payment platforms the GC has standardised on, and a large share of the facilities and property owner side runs through ordinary corporate AP portals. Either way, miss a required field or a waiver and the invoice is not late, it is absent, and the portal will not tell you. Across Monk's customer base, 92% of enterprise invoices must be submitted through a customer's AP portal rather than paid from an emailed invoice. Monk supports 600+ corporate AP portals and uploads 87% of portal invoices autonomously, including the reference fields each customer requires, so a job number or cost code that has to land in a bespoke field lands there without anyone logging in. For contractors doing commercial work at multiple sites, portal mechanics are usually the largest source of unexplained aging, and handling them is the core of AR automation for HVAC and roofing contractors. For the general version of the argument, see our guide to AP portal automation software.

What are the alternatives?

The platforms below come up repeatedly when commercial contractors evaluate this category. They are genuinely different products aimed at different buyers.

The honest way to run this evaluation is to test each product against your own worst month. Take a pay application that came back short because one change order line was held, a service invoice that could not be raised for three weeks because a signed ticket was in a van, and a finished job whose retainage nobody has chased since spring, and make every vendor walk through those three artifacts. Category positioning tells you very little. Behaviour on your actual documents tells you everything.

How does Monk handle this?

Monk treats the commercial contracting receivable as a chain that starts before the invoice, and automates each link rather than automating the reminder at the end of it.

On the cash side, AI cash application matches payments to invoices at an 80% automatic match rate, rising to 95% with suggested matching rules, and where a payment arrives short it isolates the difference against the specific invoice line rather than leaving the whole payment unapplied. That is directly useful here, because a GC paying the base contract lines and holding a change order is the most common payment you receive. It matters more broadly because 39% of cash flow slowdown is caused by edge cases, and in this vertical a held extra, a retainage release, a joint check and a waiver that was rejected are all edge cases that arrive every week.

On the outreach side, Julia, Monk's AI agent for Intelligent Collections, ingests the context of the conversation and responds to what the customer actually said rather than advancing a fixed dunning sequence. Julia reaches customers with a 24% higher response rate than standard dunning, and 90% of collections are resolved with zero human intervention. That distinction earns its keep when the reply is "this is in next month's pay app" or "we are waiting on the owner to release", neither of which is a refusal to pay and neither of which should trigger another reminder. Voice Collections is a separate product that places and receives calls about overdue invoices, working from the same customer record, which is useful when a GC's project accountant will pick up the phone but will not answer email.

The aggregate effect Monk sees across its customer base is a 40% average reduction in DSO and 26 hours a month saved on receivables work. Monk has $2B+ in accounts receivable under management, is SOC 2 Type II compliant, and integrates with QuickBooks, NetSuite, Salesforce, HubSpot and Stripe. Onboarding takes less than one week and customers see results in their first month, which matters in a business where crews are already booked and nobody can spare a controller for a long implementation.

Where should you start?

You do not need a platform decision to make progress this quarter. You need to know which of the failure modes above is holding the most of your money, and most contractors do not.

Pull your aged receivable and sort everything past terms into one bucket each: held because a change order lacks written authorisation, held because a draw was submitted without complete backup, never submitted correctly to a portal, retainage awaiting closeout, or a genuine payment problem. Then do the harder exercise, which is to list completed work orders and closed jobs with no invoice raised against them. That second list is not in your aging, and on commercial service work it is frequently larger than anything in it.

Check two structural things while you are in there. Whether you can produce, for any change order on any active job, the authorisation artifact and the date it was given, without calling the field. And whether you have a per-job calendar of notice and filing dates by state that somebody actually reviews, rather than a folder of contracts nobody has read since signing. If those answers are no, automation applied further downstream will only move the exceptions around faster.

When you are ready to compare vendors, bring the artifacts rather than the requirements document. If the shape of your problem is progress billing against a schedule of values, change orders approved on site, field paperwork that arrives late, retainage nobody owns and portals you are required to use, that is the shape Monk is built for, and AR automation for HVAC and roofing contractors is where to see how it fits your book of commercial work.