Workers' Comp Audit: Get Payroll and Subcontractor Records Ready With AI

A premium audit asks for payroll by employee and class code, quarterly payroll tax returns, a cheque register or cash disbursements journal, certificates of insurance for every subcontractor, overtime records and job descriptions. Gather them for the policy period, split payroll by hours and dollars, and let AI sort the files while your carrier makes the final call.

The audit compares the payroll you estimated when the policy began with what you actually paid, so any gap becomes extra premium or a refund. Three things within your control can move the bill: subcontractor certificates that are missing or out of date, payroll that was never split by class, and overtime recorded as one lump. Rules differ by carrier and by place, so treat this as a preparation list and ask your broker where yours differs.

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What the auditor is reconciling, and when the request arrives

A workers' compensation policy is priced on projected payroll. At the end of the term, an auditor compares that projection with the real figures and the premium is adjusted either way. One carrier's 2026 guide puts the aim neatly: to determine and collect the premium that matches your actual risk, nothing more and nothing less.

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Timing and format vary. Audits can happen at inception, midterm, expiry or cancellation. One carrier lists three formats: physical (an auditor at your premises), mail, and online with a secure upload link. Another says the method depends on premium size, type of operation and local requirements. A third tells policyholders to expect notice within 15 business days of the policy's expiry, sometimes with a questionnaire before the appointment. The practical point is that the request can arrive soon after the policy ends, so the records need to exist before it does.

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Two other things to know before you start. Payroll for audit purposes is gross pay, and one carrier's guide says the date that counts is the date the cheque was written, not the pay period it covers. And ignoring the request is expensive: one carrier's guide describes an audit non-compliance charge of 100 per cent of the estimated annual premium, reversed only after you supply everything requested and the audit is completed (partial information does not remove it). If something in your records is a mess, say so and ask for time rather than going silent.

Your carrier's own guide is the authority here, not this tutorial. Ask your broker for it, read the checklist, and use what follows to meet it. If you are still choosing codes, checking a class code against job duties explains how that decision is made, and how a renewal conversation uses the same figures is covered in gathering the figures before your broker calls.

The core record pack, item by item

These are the records that carriers' own checklists keep asking for. Assemble them for the whole policy period, including anyone who left part-way through the year, and keep every item as a file you can send within a day.

Notice what is not on the list: your best guess. Carriers verify payroll against filed returns and accept splits only when the records support them. Westfield's guidance, for one, says that splitting payroll on percentages or estimates is not permitted. That single rule shapes everything below.

Records by trade: what gets split and what the auditor tests

Every trade needs the core pack. What differs is where the questions fall. This table draws on what carriers say about classification, subcontractors and overtime, applied to the way each trade tends to work. It is a prompt for your conversation with your broker, not a ruling: your policy lists the classes it rates, and your carrier decides how they apply.

Payroll by class: why a split needs hours and dollars

Most construction policies rate one main class for the trade, with a few standard exceptions. The auditor's job is to put each person's pay in the right class, because the rates can differ enormously: a roofing class can cost many times what an office class does. Where you cannot show the split, the safe assumption for the carrier is the expensive one. One carrier's FAQ says it plainly: without an adequate breakdown, the full payroll is charged to the highest-rated classification.

Three rules from carriers' own guides are worth knowing before you build the split.

• Standard exceptions. Office clerical and outside sales staff can be rated separately only if they do essentially nothing else. One carrier's guide says employees who spend all their time in an exception class can be separately rated; another says the clerical class requires staff to be physically separated from other working areas, with duties restricted to general office work, and that an outside salesperson who also delivers product is classified accordingly.
• Construction trades. One guide allows payroll to be broken out between trades on a job (framing, drywall and plumbing in its example), but only where the breakout can be traced to your sales documents, contracts and payroll records such as time cards and job cost records. Percentage breakdowns are not allowed. Westfield's guidance says the same: payroll splits are allowed in some cases when proper records exist, but splitting on percentages or estimates is not permitted.
• Supervisors and owners. A class for executive supervisors does not apply, in one carrier's words, to anyone directly in charge of daily construction activities. A working owner who leads a crew on site is unlikely to qualify for an executive class, whatever the job title says, but the carrier decides.

The practical consequence is that "we split it roughly 80/20" is worthless at audit, while "here are 11,400 logged hours by job, with the class of work noted on each time card" is exactly what the auditor wants. If you are not logging class of work on time cards today, start with the next pay period. A split built from last year's memory is not something an AI can fix.

One remodeller's year: the same audit, unprepared and ready

The firm in this example is invented: a remodeller with six field staff and two office staff, a 1 January to 31 December policy and five subcontractors. All rates below are made up for the sum; your policy shows the actual classes and rates.

The subcontractor payments for the year came to $55,000 in all, in five lines:

Now the two audits. In the unprepared version there is no class split, no overtime record and the two missing certificates: all $278,000 of payroll goes to the field class (a $26,410 charge at $9.50 per $100), plus $25,000 of subcontractor payments treated as payroll (another $2,375). Total: $28,785.

In the ready version, the office payroll sits in the office class ($41,600 at $0.15 per $100 is $62.40). The overtime premium is excluded: at time and a half one third of the overtime pay, $6,400, comes off, leaving $230,000 of field payroll and a charge of $21,850. Only the $11,000 labourer remains as subcontractor payroll, costing $1,045. Total: $22,957.40.

The difference is $5,827.60, and every dollar of it comes from paperwork rather than from the work done. Splitting out the office costs only some record-keeping and saves about $3,890 on the sums above (the $41,600 would otherwise be charged at the field rate). The two certificates are worth $1,330 (the $14,000 not treated as payroll, at the field rate). The overtime exclusion adds $608. Before you trust any of this for your own policy, confirm with your carrier that each rule applies: overtime exclusion is not allowed everywhere, and class acceptance depends on duties.

Overtime: the third you may be able to take off

Overtime pay counts as payroll, but the premium part of it usually need not. Where the rule applies, one third of overtime pay at time and a half and one half at double time can come off the audited payroll, because the straight-time value of those hours is still payroll and only the extra is excluded. Carriers attach a condition, and it is nearly always the same: your records must show overtime separately. One carrier's FAQ asks for overtime pay by employee and in summary by class of work. The reduction does not apply everywhere, so ask your carrier before you count on it.

A quick sum for one carpenter: $30 an hour straight time, 100 overtime hours at time and a half. Overtime pay is 100 times $45, or $4,500. Of that, $1,500 is the half-time portion that can be excluded (100 hours times $15). The other $3,000 stays in payroll. At double time the same 100 hours would be $6,000, of which $3,000 is excludable.

What goes wrong is rarely the sum. It is the record: a payroll report that shows total pay per person with overtime buried inside it, or an overtime column in hours not dollars, or overtime paid at two different multiples with no note of which. Ask your payroll provider for a report with straight-time pay, overtime pay and double-time pay in separate columns per employee and per class, and check that the sum of the columns equals gross pay. If your system cannot produce it, build it from the register and time cards with the time-card prompt later in this tutorial.

Subcontractor certificates: eight checks before a payment goes out

A certificate is a one-page record that a subcontractor has workers' compensation cover, issued by their insurance agent. The auditor looks at it to decide whether the money you paid that subcontractor is their risk or yours. Carriers' guides give a short list of things that make a certificate good enough, and the useful habit is to check them when you first engage the subcontractor, not at audit time.

1. It came from the agent or insurer. One guide recommends an original, obtained directly from the producer or insurer, which also lets the certificate holder receive a notice if the policy is cancelled, where the insurer offers one. A written statement from the subcontractor is not adequate proof.
2. The insured is the person you pay. If you pay a named individual or company, that exact name must be the insured on the certificate.
3. It shows a policy number, not a binder number. A binder shows an intention to buy; if the payment never lands, the policy may never start.
4. The dates cover the work. The policy period must match when the work was performed, as closely as possible. Keep a certificate for each policy year the subcontractor worked for you.
5. The cover applies where the work happens. If the insured's address is somewhere else, confirm in writing through the agent or insurer that your site's location is covered.
6. The contract exists. A written subcontract for each job, naming the scope and the price.
7. Invoices split labour from materials. If a certificate turns out to be missing, a carrier may look at the contract and the invoices to decide what portion counts.
8. The next expiry is in your diary. A certificate is a snapshot. Note the expiry date and request the renewal a month early.

Checks six and seven matter most when a certificate is missing, because of how carriers treat an uninsured subcontractor. One carrier's guide says the amount assessed will not be less than 50 per cent of the contract price when the subcontractor supplies all material and labour for the whole job, 100 per cent where only labour is provided, one third where mobile equipment with operators is supplied, and 100 per cent of the amount paid where there is no contract at all. Another carrier says simply that without a valid certificate it may charge premium for the work. These are separate carriers' rules, so yours may be different, but the pattern holds: a contract and a labour and materials split can reduce what is counted, and no paperwork at all counts the lot. A related point from the same guide: an individual who does "crew" work such as framing, siding, roofing, drywall or concrete may be treated as an uninsured subcontractor even when they supply all their own materials.

A tracker the AI can check for you

Keep one row per subcontractor, typed from each certificate. The AI then does the dull comparison of dates and names that people skip. It is a checker, not a judge: it can say a certificate expired before your last payment, and it cannot say whether the cover is adequate or whether your carrier will accept it. Remove personal details first and use short codes for payees.

Below are fields I typed from workers' compensation certificates, plus my payment dates. Dates are day/month/year.
Columns: sub code, trade, payee name I pay, insured name on certificate, policy number as printed, cover from, cover to, first payment, last payment, written contract (Y/N).
For each row flag: (1) cover ends before the last payment; (2) cover starts after the first payment; (3) insured name differs from payee name; (4) the policy number text says "binder" or "pending"; (5) no certificate or no contract.
Output a table with one flag column and one line of action per row. Do not comment on whether the cover is adequate.
[paste rows]

Here the AI's first pass wrongly flagged S2 as "cover starts after the first payment", because it read 04/03 as 3 April instead of 4 March. That is the usual failure with certificates: ambiguous dates. The fix is the first line of the prompt, which states the date format, and a rule to confirm any flag against the certificate itself. Then send the request below to any subcontractor with a gap; it fits in a text or email.

Hi [first name], could you ask your insurance agent to email me your current workers' compensation certificate? It needs to show a policy number (not a binder), [exact name] as the insured, and dates that cover [months] of this year. If you used a different policy earlier in the year I'll need that one as well. Thanks, [your name].

For a fuller onboarding routine, including reminders before certificates expire, see tracking subcontractor insurance expiry and onboarding, and for the wider paperwork round, the subcontractor paperwork chasing checklist.

Sorting the cheque register: a prompt and what it gets wrong

The auditor will read your cheque register or cash disbursements journal looking for labour paid outside payroll. You can beat them to it. Export a year of payments (date, payee, memo, amount), swap payee names for codes in a spare column, and ask the AI for a first sort. If the export is messy, clean it first, for example with the steps in cleaning messy data.

Here is a year of payments (date, payee code, memo, amount). Tag each as: LABOUR_SUB, MATERIALS, EQUIPMENT_HIRE, PAYROLL_PROVIDER, OWNER_DRAW, OTHER.
Where a memo mixes labour and materials, tag it LABOUR_SUB and add "mixed" in the note.
Then list every payee tagged LABOUR_SUB with its total for the year and whether the payee code appears in my certificate list: [paste list of codes with certificates].
Mark uncertain tags "check" with one line of reason. Do not guess.

Expect two kinds of error. The AI over-tags (anything with "fit" or "driver" in the memo can become labour), and it under-tags (a payee called "Supplies" can hide a labour element). The "check" instruction exists so it admits doubt rather than guessing. Review every LABOUR_SUB line and a sample of 20 from the rest, and treat the list of payees without certificates as your chasing list.

Time cards to payroll by employee and class

This is the prompt that turns the "hours and dollars" rule into a table. It needs time cards or a timekeeping export with the class of work on each line. Use employee numbers, not names, and think twice about including pay rates on a personal plan (see the privacy section below).

Below are weekly time-card lines for one policy year: employee number, week ending (day/month/year), job code, class of work (FIELD or OFFICE), straight hours, overtime hours, hourly rate, overtime multiplier (1.5 or 2).
For each employee and class give: straight pay, overtime pay, the excludable part of overtime pay (one third of overtime pay at 1.5, one half at 2), and total gross.
Then give company totals by class, and a reconciliation line against this gross payroll figure from the register: $[figure].
Show any difference and list the three biggest candidates for the gap. Do not round until the last step.
[paste lines]

An illustrative result for the remodeller above: from the time cards the field class comes out at $216,900 straight-time pay and $19,200 overtime pay, with $6,400 excludable, a total of $236,100 against a register figure of $236,400. The gap is $300. Its three candidates are a missed week, a rate change and a bonus; the true cause is a one-off bonus paid through the payroll provider that never touched the time cards.

That last point is the lesson of the reconciliation. The register is the master document, because the auditor tests it against your filed tax returns. Time cards support the split by class, they do not replace the register. When the two differ, find the difference and write one line of explanation in the file. Bonuses, commissions and holiday or sick pay are all part of payroll even though they never appear on a job time card. For expense reimbursements and flat expense allowances, one carrier's guide says they count as payroll unless three conditions are met: the expense was for the business, each employee's amount is recorded separately, and it is a fair estimate of the real cost. The same guide lists allowances for hand tools and hand-held power tools as payroll in every case, so do not plan on excluding those.

Two safeguards keep the arithmetic honest. First, ask for the formulas as well as the figures, and rebuild the totals in a spreadsheet with a pivot table; the AI's role is the layout and the cross-check, not the final number. Second, spot-check three employees by hand: multiply one week's hours by the rate, add the overtime at its multiplier, and compare. If those three agree, the rest usually will; if one does not, find out why before you trust the total.

Keep pay data out of the chat

Payroll files hold the most sensitive information a small firm has. The audit does not require you to feed any of it to an AI, so share only what the task needs. Strip names, government ID numbers, bank details, home addresses and dates of birth, and replace people with employee numbers. Keep the key that links numbers to names in a separate file that never leaves your computer. For the sort in this tutorial the AI needs dates, hours, rates, codes and amounts, nothing more.

Check the plan you are using, too. Business plans such as ChatGPT Business or Enterprise, and Claude Team or Enterprise, do not train on your content by default, according to the vendors' terms as last checked. Personal plans work differently: ChatGPT, for example, has an "Improve the model for everyone" switch under Data controls, so check how it is set before you paste anything sensitive. If you are not sure which applies, treat the chat as public and strip more. Where the figure is pure arithmetic, a spreadsheet formula needs no AI at all.

Owners, officers and office staff: read the policy, not the AI

Carriers ask for the pay and duties of owners and officers, and the rules differ on whether they are covered. One carrier's page says that some places let officers elect exclusion from coverage, and that sole proprietors, LLC members and partners may be endorsed to include or exclude, depending on local rules. Another asks for a list of officers and their responsibilities with the records. Your policy's endorsements say whether each owner is included or excluded and at what payroll basis, so check them before the audit and list every owner, with their role and hours on site.

Likewise for office staff: write one short paragraph per person that says what they do all day, and whether they ever visit a site. One carrier warns that the clerical class carries restrictions on how separate the work must be, and that salespeople who also deliver are rated for what they do. The AI can tidy your wording into a clear job description if you give it the facts, but the carrier's auditor will ask the person, so the paragraph must match what really happens.

Five mistakes that raised a premium, and how each showed up

These are illustrative, built from the rules in the carriers' guides, and each one is cheap to prevent.

1. The certificate that started in June. A joiner was paid from March, but the only certificate on file began on 1 June. It showed up on the audit worksheet as three months of payments counted as payroll. The fix is to see a certificate before the first payment and to ask for the previous year's as well.
2. Overtime in hours. The payroll report showed overtime hours and a single gross pay figure per person. The auditor could not isolate the overtime dollars, so none were excluded. The fix is a report with straight-time, overtime and double-time pay in separate dollar columns.
3. The missing leaver. The payroll provider's report defaulted to current employees, so two people who left in the autumn were absent. Payroll came in below the filed returns and the auditor asked for the difference. Carriers ask for everyone paid in the period, terminated staff included.
4. The guessed split. The office was said to be "about 15 per cent of payroll". With no hours or dollars to back it, the whole payroll went to the higher class. The fix is a class of work on every time card and a separate pay record for people who work only in the office.
5. The travel allowance in the wages. A flat $25 a week "travel allowance" was paid with wages and not shown separately. Without a separate record per employee and a mileage log showing it matched real costs, it counted as payroll. The fix is a separate line per person and the log behind it. (A hand-tool allowance would have counted as payroll either way under one carrier's rules.)

Run your own file through the same five questions each year-end. An AI can do the pass in a minute if you give it the register summary, the certificate tracker and the time-card totals, and ask it to list anything that resembles one of these. It will also invent problems, so check each item against the paper before acting.

If the audit result looks wrong: build the evidence first

When the carrier's worksheet arrives, compare it with your own pack line by line: total payroll against the register, each class against your split, each subcontractor payment against the tracker, overtime against the excludable figure. If a difference is wrong in your favour, tell your broker anyway; if it is wrong against you, you need evidence, not argument. One carrier's dispute form lists what it wants, and the lists make a useful template for any carrier.

• Disputing a class: the employees' names, written job descriptions in detail, the wages in question and the records that support them.
• Disputing an uninsured subcontractor charge: the subcontractor's name, certificates of workers' compensation and general liability insurance, a copy of their business licence and a written subcontract for each job. Add invoices that separate labour from materials from your own file; the form does not ask for them, but they support any argument about what portion was labour.
• Anything else: a clear explanation, the supporting payroll, and contracts if it is a construction risk.

A short cover letter that points to numbered documents is easier to read than a long email, and the AI can draft it from your facts. Give it the figures and the document list, and tell it to add nothing.

Draft a one-page letter to the carrier's audit dispute team about policy [number].
Facts: the audit worksheet counts $9,000 paid to subcontractor S3 as payroll; we have a certificate covering the dates of the work (document 1), a signed subcontract (document 2) and invoices splitting labour and materials (document 3).
Ask the carrier to remove the $9,000 and to confirm in writing. Use only these facts and these three documents; do not add legal arguments or dates I have not given you. Under 250 words.

Procedures, time limits and who decides vary by carrier and by place, so ask your broker how a dispute works on your policy before the deadline starts to run. Do not leave it until the payment is due.

A year-round routine that makes the audit an afternoon

Keep the pack in one folder per policy year, with the same subfolders each time: payroll, tax returns, subcontractors, overtime, job descriptions and correspondence. The quarterly reconciliation is an easy step to skip, and it is the one that can turn up a surprise before the auditor does. Done this way, the audit stops being an event and becomes an afternoon of exporting what already exists. The AI sorts and drafts, you check against the paper, and your carrier decides what counts.

Questions contractors ask about a workers' comp audit

When will my workers' comp audit happen?

Usually after the policy ends, though some carriers also audit at inception, midterm or cancellation. One carrier's guide says to expect notice within 15 business days of expiry. Audits may be on site, by mail, or online and by phone, depending on premium size and type of operation. Ask your carrier which applies and what it needs first.

What if I cannot find a subcontractor's certificate of insurance?

Ask the subcontractor's agent for a copy covering the dates they worked for you. Carriers can charge premium on payments to uninsured subcontractors, and one carrier's guide says a written statement is not proof of coverage. Collect certificates during the year, not at audit time, and keep invoices that split labour from materials.

Can I exclude overtime from my audited payroll?

Often only the premium portion can be excluded: one third of overtime pay at time and a half, one half at double time. It generally requires records showing overtime separately by employee and class, and a few places do not allow the reduction at all. Ask your carrier whether it applies to your policy.

Is it safe to upload payroll files to ChatGPT or Claude?

Strip names, government ID numbers, bank details and home addresses first, and use employee numbers instead. Business plans such as ChatGPT Business and Claude Team do not train on business content by default, but check your plan's data settings. For pure arithmetic, a spreadsheet formula needs no AI at all.

Further reads

• ChatGPT for Payroll Teams: Safe Prompts That Never Include Pay Data — Safe prompts that never include pay data.
• AI Payroll Checks: Catch Timesheet Errors Before Payday — Catching timesheet errors before they reach the audit.
• Subcontractor Prequalification Questionnaire: Build and Score It With AI — Vetting subcontractors before the first job.
• AI for Building Contractors: Chasing Subcontractors and Progress Updates — Chasing subcontractors for documents without nagging.
• Can ChatGPT Draft a Subcontractor Agreement? Clauses to Check — Clauses that make the insurance paperwork enforceable.
• General Liability Audit for Contractors: What the Auditor Asks For — What a general liability premium audit asks a contractor for, and how to gather gross receipts, subcontract costs and certificates before the auditor calls.
• AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.

Sources: published premium audit guides and pages from several workers' compensation carriers (checked November 2026), and the AI vendors' business data-use terms (checked October 2026). Rates, payrolls and premiums in the worked example are invented for illustration.