Most subs lose thousands every year to invoices that quietly slip past 90 days. Here's how to stop that from happening without hiring a bookkeeper or becoming a spreadsheet wizard.
If you run a plumbing crew, an electrical shop, or an HVAC outfit, your day ends covered in drywall dust, not sitting at a desk reviewing receivables. The invoice goes out when it goes out. The follow-up happens when you remember. And by the time you check, that net-30 invoice from March is sitting at 87 days and nobody's said a word about it.
That's not a discipline problem. That's a systems problem. And it's costing you real money.
Accounts receivable aging is a breakdown of every unpaid invoice by how long it's been outstanding. The standard buckets:
0-30 days. This is healthy. The invoice is out, the GC has it, payment is expected on time.
Yellow flag. One follow-up should have gone out. If the GC hasn't acknowledged, something is wrong.
Red flag. This invoice needs a phone call, not an email. The GC's AP team may have lost it or deprioritized it.
Danger zone. Collection rates drop hard here. Many subs quietly write these off. That's money you earned and never collected.
The number that matters most is your 90+ bucket total. If that number is growing month over month, you have a collection problem that's eating into your cash flow whether you feel it yet or not.
Most subs start with a spreadsheet. Invoice number, date sent, amount, GC name, "paid?" column. It works until it doesn't. The problems show up around invoice number 50:
The spreadsheet doesn't tell you when an invoice crosses from 30 to 60 days. It doesn't send follow-up emails on a schedule. It doesn't flag which GC is a chronic slow-payer. It doesn't connect your AR to your compliance documents, so you don't notice that the GC who owes you $14,000 also has an expired COI on file. And it definitely doesn't calculate your weighted average collection period so you can see whether things are getting better or worse.
A spreadsheet records what happened. It doesn't prevent what's about to happen. For a two-person shop, maybe that's fine. For anyone running multiple jobs with multiple GCs, it's a liability.
Whether you use software or a disciplined manual process, your AR tracking needs to handle five things:
Every invoice should land in the right bucket (current, 31-60, 61-90, 90+) without you doing math. The system moves invoices between buckets based on the calendar, not on when you remember to check.
A friendly reminder at day 30. A firmer one at day 45. A direct one at day 60. These should go out on schedule whether you're on the jobsite or not. The GC's AP department expects them. Your silence is their permission to delay.
Some GCs pay on day 28 like clockwork. Some GCs say net-30 and mean net-75. You need to know which is which before you take the next job from them, not after you've already done the work.
You need to see aging by individual job (how much is outstanding on the Riverside project?) and by GC (how much does ABC Construction owe me across all jobs?). One view isn't enough. You need both.
Your AR aging feeds directly into your cash flow picture. If $40,000 is sitting in the 61-90 bucket, that's $40,000 you can't use for payroll, materials, or equipment. Your AR system should make that connection obvious, not leave it as a number you have to interpret.
For trade subcontractors, AR aging isn't an accounting exercise. It's the difference between making payroll and scrambling. Every invoice that ages past 90 days is money you earned on a jobsite, with your hands, that you may never see.
The fix isn't complicated. It's consistent. Set up a system that watches your aging buckets, sends reminders on schedule, and shows you which GCs are reliable and which ones aren't. Then trust the system and focus on the work.
That's what STUDD was built to do. One platform. Invoicing, AR aging, automated follow-ups, GC payment tracking, compliance. Set it up once, and the back office runs while you're on the jobsite.
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Read →What GC AP departments actually want to see on a sub invoice, and how to send one that gets paid faster.
Read →What you gain and what you give up when you move from Excel to purpose-built sub management software.
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