Cost-Plus Construction Invoices and Records Ontario

Ontario cost-plus contractsInvoices and audit recordsCost of Work + contractor fee

Cost-Plus Construction Invoices and Records in Ontario

Cost-plus does not mean “send a total and trust the builder.” The contract should define every chargeable cost, every excluded overhead item, the exact contractor-fee formula, the backup required with each invoice, how credits are handled and how the projected final price is updated before the budget is gone.

Scan My Contract Free Fixed Price vs. Cost-Plus Draw Schedule Guide

16 partsControlled billing clause

12 recordsInvoice support package

7 days2026 proper-invoice deficiency notice

14 daysTypical owner non-payment notice deadline

A statutory proper invoice is not automatically a complete cost-plus accounting.

The Construction Act controls prompt-payment requirements. The contract must separately require the detailed source records, audit access, fee calculations, credits and forecasts needed to verify actual cost.

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Include the fee schedule, labour rates, equipment rates, subcontractor backup, cost reports, changes, credits and disputed charges.

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Four numbers every cost-plus invoice must separate

Direct Cost of WorkLabour, materials, equipment, subcontractors and other items expressly included by the contract.

Contractor feeA percentage, fixed fee, hourly management charge or combination applied exactly as the contract states.

Excluded overheadOffice rent, ordinary estimating, accounting, vehicles, phones and general business expense unless expressly chargeable.

Credits and recoveriesReturns, rebates, discounts, supplier credits, insurance proceeds and other project recoveries that should reduce cost where required.

Do not accept one blended total. The invoice should show direct cost, contractor fee, HST, credits, statutory holdback and prior payments separately.

The 16 parts of a controlled cost-plus billing clause

Definition of Cost of Work

Critical

Define: List included labour, materials, subcontractors, equipment, testing, permits, temporary work and project-specific services.

Control: List excluded overhead, financing, estimating, rework, fines, unrelated costs and contractor-caused waste.

Contractor fee

Money

Define: State percentage, fixed fee or hourly management fee and when it is earned.

Control: Define whether fee applies to labour burden, subcontractor markup, tax, insurance, change work and credits.

Labour billing

Money

Define: Identify employees, trades, time-sheet fields, regular and overtime authorization.

Control: State whether billing uses actual payroll cost, agreed composite rates or another formula.

Payroll burden

Money

Define: Define CPP, EI, vacation, WSIB, benefits and other permitted burden components.

Control: Prevent a burden percentage from being added on top of rates that already include it.

Subcontractor costs

Critical

Define: Require original invoices, scope reference, payment status and embedded fee disclosure.

Control: State whether contractor fee applies to the net invoice before HST and after credits.

Material costs

Money

Define: Require supplier invoice, delivery location, quantity and project connection.

Control: Address freight, small tools, consumables, waste, restocking and unused material.

Equipment costs

Money

Define: Define owned versus rented equipment, operator, fuel, minimum time and standby.

Control: Use agreed rates and prevent charges for idle or contractor-convenience equipment.

Travel and vehicles

Critical

Define: State whether mileage, delivery, travel time, parking and tolls are chargeable.

Control: Exclude ordinary commuting and duplicate vehicle overhead unless expressly agreed.

Credits and rebates

Money

Define: Require prompt credit for returns, discounts, rebates, refunds and recoveries.

Control: State whether credits reduce the fee base as well as direct cost.

Supporting records

Process

Define: List documents delivered with every invoice and acceptable electronic format.

Control: Require legible project coding and prohibit summaries without source records.

Monthly cost report

Process

Define: Show original budget, approved changes, committed cost, actual cost and forecast.

Control: Require explanation of variance and projected final contract price.

Budget warning

Critical

Define: Set a dollar or percentage threshold requiring written warning before commitment.

Control: No silence-until-invoice approach when overrun is reasonably foreseeable.

Invoice review period

Process

Define: Coordinate contract review requirements with Ontario proper-invoice rules.

Control: Identify where notices must be sent and who has authority to approve or dispute.

Audit right

Process

Define: Define scope, timing, location, electronic access and independent accountant use.

Control: Protect unrelated confidential information while preserving project verification.

Disputed charges

Process

Define: Require timely written reasons and payment of undisputed amounts where applicable.

Control: Preserve adjudication, negotiation and other contract remedies without self-help confusion.

Record retention

Process

Define: State how long project records must be kept after completion or termination.

Control: Require records to survive contractor change, insolvency, audit and warranty disputes.

Twelve records that should support the invoice

Contract and cost schedule
Defines Cost of Work, exclusions, fee base and billing procedure.

Subcontractor invoice
Legal supplier name, date, scope, quantity, taxes and project reference.

Material invoice
Product, quantity, unit price, delivery location, freight, return and credit details.

Labour time sheet
Worker, trade, date, task, regular/overtime hours and agreed billing rate.

Payroll support
Actual wage, burden or agreed composite rate where the contract allows review.

Equipment log
Machine, operator, attachment, date, productive time, standby and rate.

Delivery and disposal tickets
Truck, source, destination, quantity, weight, waiting and disposal charge.

Purchase order
Who authorized the cost and how it connects to the contract scope or change.

Change order
Owner approval, budget effect, contractor fee, schedule effect and credit treatment.

Monthly cost report
Budget, committed cost, actual cost, forecast-to-complete and projected final price.

Credit register
Returns, rebates, volume discounts, cancelled orders and supplier adjustments.

Payment proof
Evidence that invoiced subcontractor and supplier obligations were paid or remain outstanding.

How the invoice should calculate

Percentage feeIllustrative eligible Cost of Work of CAD $100,000 and a 15% contractor fee.CAD $100,000 + CAD $15,000 fee = CAD $115,000 before tax and holdback

Credit reduces costCAD $8,000 material return on cost previously included in the fee base.Credit direct cost and related fee treatment as contract requires

Duplicate-markup testSubcontractor invoice includes its own overhead and profit; general contractor adds 15% only if authorized.Check embedded sub markup before adding GC fee

Forecast to completeActual CAD $450,000 + committed CAD $180,000 + estimated remaining CAD $120,000.Projected cost before fee = CAD $750,000

Illustrations only. There is no universal Ontario contractor markup or standard Cost-of-Work formula. The signed contract controls.

Proper invoices and the 2026 Ontario deadlines

Rule	Current Ontario requirement	Cost-plus contract lesson
Proper-invoice content	Contractor identity, invoice date and payment entitlement, contract or authorization reference, supplied work or materials including quantity where appropriate, amount, terms and payment-contact information.	Project coding and cost backup should be required in addition to statutory minimum content.
Seven-day deficiency notice	Since January 1, 2026, an invoice that misses proper-invoice requirements is deemed proper unless the owner gives written notice of the deficiency and required correction within seven days.	Assign one reviewer and a reliable email or notice address. Do not leave invoices unopened.
Owner payment	Where prompt-payment provisions apply, the owner pays the payable amount no later than 28 days after receiving the proper invoice.	The contract should align document review with the statutory clock.
Disputed amount	The owner generally gives the prescribed notice of non-payment within 14 days, stating the unpaid amount and all reasons.	A casual email saying “need more backup” may not replace the required statutory notice.
Undisputed amount	The amount not covered by a valid notice remains payable under the prompt-payment rules.	Separate unsupported or disputed charges from the balance that is properly payable.

Do not confuse a seven-day invoice-deficiency notice with a 14-day payment dispute.

They address different problems and may require different wording and forms. Ontario legal advice is appropriate before withholding a significant invoice.

Trust records are not the same as owner audit rights

Ontario’s Construction Act treats amounts owing or received by contractors and subcontractors on account of an improvement as trust funds for qualifying downstream suppliers. Trustees must deposit trust funds into an account in the trustee’s name and maintain written records of receipts, payments, transfers and other prescribed information.

That statutory bookkeeping duty does not automatically mean a homeowner can inspect every bank statement, payroll file or unrelated business record on demand. A cost-plus contract should create a project-specific audit right that identifies:

which source documents may be inspected;
how confidential employee and unrelated-project information will be protected;
whether electronic copies are sufficient;
when the audit may occur and who pays for it;
what happens when an overcharge is found; and
how long the records remain available after completion or termination.

Project trust records and cost substantiation overlap—but they are not identical. Have a lawyer draft access rights rather than assuming the statute supplies the complete audit clause.

Bad wording versus controlled wording

Bad: cost plus whatever the builder charges

“The Owner shall pay all costs incurred by the Contractor plus 20%. The Contractor’s monthly statement is conclusive, and supporting invoices will be provided when available.”

Better: defined cost and current records

“The Owner shall pay only the Cost of Work categories listed in Schedule C plus the Contractor Fee stated in Schedule F. Each invoice shall identify the contractual authority, billing period, direct cost, fee, HST, holdback, credits and prior payments and shall include the supporting records listed in Schedule R. Project-specific returns, rebates, discounts and recoveries shall be credited as stated in Schedule C. The Contractor shall provide an updated budget, committed-cost report and forecast to complete with each monthly invoice and written warning before committing a cost expected to exceed the approved category budget by the stated threshold. The Owner may audit project records during the Work and for the stated retention period, subject to reasonable confidentiality protections.”

Educational example only. An Ontario lawyer and accountant should adapt Cost of Work, taxes, payroll burden, prompt payment, audit and record-retention wording.

A cost-plus invoice without source records is still a request—not proof.

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Eight cost-plus billing red flags

One-line monthly invoice
The owner receives only “costs this month” with no supporting schedule or records.

Markup on markup
The contractor adds a fee to a subcontractor invoice that already includes an undisclosed general-contractor markup.

Office overhead billed twice
General overhead is included in the contractor fee and also charged as project cost.

Unidentified labour
Time sheets say only “site work” with no worker, task, date or hours.

No supplier credits
Returned materials, rebates and discounts disappear instead of reducing project cost.

Owned equipment billed as a rental
The contract does not define the rate, included fuel, operator or comparison with market cost.

Actual cost confused with estimate
A budget allowance becomes an automatic charge even when the underlying cost was lower.

Audit right after final payment only
The owner cannot catch errors while they can still be corrected or offset.

Ontario consumer and record-keeping checks

Written renovation contract: Ontario says home-renovation contracts worth more than CAD $50 must be in writing and should contain a thorough work description, itemized products and services, total cost and payment terms.
Estimate rule: If an estimate forms part of a qualifying consumer agreement, Ontario guidance says the final price generally cannot exceed it by more than 10% unless the consumer agrees to new work or a new price. A true cost-plus arrangement must be drafted carefully rather than relying on the label alone.
Proper-invoice rules: Where the Construction Act prompt-payment regime applies, invoice content, seven-day deficiency notice, 28-day payment and 14-day non-payment notice rules can affect how invoice disputes are administered.
Trust records: Contractor and subcontractor trustees must maintain written records of project trust-fund receipts, payments and transfers.
Tax records: The Canada Revenue Agency requires businesses to keep records supporting income and expense claims, including invoices, agreements, statements, vouchers and proof of transactions.

None of these rules replaces a detailed cost-plus contract.

Tax records, trust records, proper invoices and owner audit records serve different purposes and do not automatically create identical access rights.

Official references: Ontario Construction Act, Ontario renovation rights, Ontario contractor guidance, and CRA business-record guidance.

Twenty-four questions before accepting cost-plus billing

What exactly is Cost of Work?

Which costs are expressly excluded?

Is the contractor fee fixed or percentage?

What amount forms the fee base?

Does the fee apply to HST?

Does the fee apply to contractor labour?

Does the fee apply to subcontractor markup?

Are overhead and supervision already in the fee?

What labour rates apply?

Are payroll burdens itemized or built in?

How is overtime approved?

How is owned equipment priced?

Are travel and delivery chargeable?

Are waste and rework chargeable?

Who receives rebates and discounts?

How are returns credited?

What supporting records accompany each invoice?

How many days does the owner have to review?

What is the audit procedure?

Can records be inspected electronically?

How often is the forecast updated?

What warning is required before budget overrun?

How are disputed costs handled?

How long must project records be retained?

Contract Centre and related guides

Cost-plus invoices and records FAQ

Does a cost-plus contractor have to provide every supplier invoice?

The contract should say so. Ontario’s Construction Act defines what a proper invoice must contain, but it does not automatically turn every cost-plus agreement into an unlimited owner audit right. Detailed access should be written into the contract.

What is normally included in Cost of Work?

Common categories include project labour, materials, subcontractors, equipment and project-specific services, but there is no universal list. The signed agreement controls.

Can the contractor mark up subcontractor invoices?

Yes if the contract authorizes the fee and clearly states the percentage and cost base. The owner should check for duplicate or hidden markup already embedded in subcontractor pricing.

Should rebates and discounts go to the owner?

The contract should decide. In a transparent actual-cost arrangement, project-specific credits, returns and rebates are usually addressed expressly so the contractor does not charge gross cost while keeping the recovery.

Can an owner refuse an unsupported invoice?

The owner may have contract rights and, where prompt-payment rules apply, statutory notice obligations. Since January 1, 2026, an invoice can be deemed proper unless the owner identifies a proper-invoice deficiency in writing within seven days; a payment dispute generally requires the prescribed non-payment notice within 14 days.

Is a proper invoice the same as a fully substantiated cost-plus invoice?

No. A statutory proper invoice starts the prompt-payment process. The contract may require additional backup for commercial review and audit, but those requirements must be drafted and administered carefully.

How often should the contractor update the budget?

A useful cost-plus contract requires regular actual-cost, committed-cost and forecast-to-complete reporting—commonly with each billing cycle. The exact cadence is contractual, not a universal Ontario rule.

Can the owner inspect the contractor’s trust records?

Ontario law requires contractor and subcontractor trustees to maintain written trust-fund records, but that does not automatically give every owner unrestricted access. Contract audit rights, litigation disclosure and legal remedies are separate questions.

Cost-plus works only when the records arrive before the surprises

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Reviewed July 30, 2026. General educational information only. This page is not legal, tax or accounting advice and does not determine whether a specific invoice is payable.