The short version
In Alberta, a "proper invoice" is the bill the general contractor gives the owner under section 32.1 of the Prompt Payment and Construction Lien Act. It has to contain seven listed items, and it starts every payment clock on the job. Read literally, the Act does not require a subcontractor's invoice to the GC to be a proper invoice: your 7-day and 35-day clocks run from the GC's proper invoice to the owner, once your work is included in it. Your practical job is to get your bill to the GC in time to be included, with every item the Act lists.
- 7 items must be on a proper invoice, including a statement that it is intended to be a proper invoice (s. 32.1(1)).
- Proper invoices go to the owner at least every 31 days, unless testing and commissioning conditions in the contract are not met (s. 32.1(6)).
- The owner pays within 28 days of receiving a proper invoice (s. 32.2(1)).
- Your clock: 7 days after the GC is paid, or 35 days after the GC gave the owner the proper invoice that included your work (s. 32.3).
- The Act's 10% holdback is the owner's obligation (s. 18). How you show holdback on your own invoice is set by your subcontract.
For the full set of payment deadlines, notices and liens, see the prompt payment and holdback overview.
Does a subcontractor's invoice to the GC have to be a "proper invoice"?
The Act's wording points to no. Three things in the text tie the proper invoice to the owner and contractor level:
- The definition names the contractor. Item (a) of s. 32.1(1) is "the contractor's name and business address". Section 1(b) defines a contractor as a person contracting with, or employed directly by, the owner. A subcontractor is defined separately (s. 1(n)).
- The 31-day rule is about the owner. Section 32.1(6) says proper invoices must be given "to an owner".
- Your deadlines count from the owner invoice. Section 32.3 makes the GC pay you for work "included in the proper invoice", either 7 days after the owner pays or 35 days "after giving the proper invoice to the owner". If you have your own subs, their fallback date under s. 32.5(5) is 42 days after the proper invoice was given to the owner.
So the event that starts your clock is not the day you send your invoice. It is the day the GC gives the owner a proper invoice that includes your work. If your bill misses the GC's cut-off, your work rides on the next one, and your clock starts up to a month later.
One caution: your subcontract can set its own invoicing rules, and s. 32.1(1) lets a contract add requirements. If real money turns on the question, get advice.
The simple answer in practice: put every s. 32.1 item on your invoice anyway. It costs nothing, it gives the GC what it needs to roll your work into its own proper invoice, and it gives you a clean document if the amount ends up in adjudication.
If you have subs of your own and must pay them under s. 32.5, the GC must, on your request, confirm the date it gave the owner the proper invoice, as soon as possible (s. 32.5(10)).
What has to be on a proper invoice?
Section 32.1(1) lists these items. The bill must be written, and it must also meet any other requirements in the contract.
| Item | What the Act says | Section |
|---|---|---|
| 1 | Contractor's name and business address | 32.1(1)(a) |
| 2 | Date of the invoice and the period the work was done or materials furnished | 32.1(1)(b) |
| 3 | Information identifying the authority for the work, "whether in a written or verbal contract or otherwise" | 32.1(1)(c) |
| 4 | Description of the work done or materials furnished | 32.1(1)(d) |
| 5 | Amount requested and the payment terms, broken down for the work or materials | 32.1(1)(e) |
| 6 | Name, title and contact information of the person payment is sent to | 32.1(1)(f) |
| 7 | A statement that the invoice is intended to be a proper invoice | 32.1(1)(g) |
Item (h) allows the regulations to add more. As of the November 26, 2025 consolidation of the Prompt Payment and Adjudication Regulation, none is added.
The 31-day rule and the testing and commissioning exception
Proper invoices must go to the owner at least every 31 days (s. 32.1(6)). The owner and GC can agree when in the cycle invoices are delivered, but only inside that 31-day limit (Regulation s. 3).
A contract clause that makes the giving of a proper invoice depend on someone's prior certification, or on the owner's prior approval, is of no force or effect (s. 32.1(3)). The exception is a clause providing for testing and commissioning (s. 32.1(4)). Where the contract has one and those conditions are not met, the 31-day rule does not apply either.
So a consultant's sign-off cannot lawfully hold up the GC's invoice for ordinary progress work, but a scope tied to commissioning may bill on a different rhythm. Check your subcontract.
How do I time my invoice to the GC's billing cycle?
Ask the GC three questions at the start of the job, and get the answers in writing:
- What day of the month does it invoice the owner?
- What is its cut-off for sub invoices to be included?
- Does it want your invoice in a set format or through a portal?
Then send your bill before the cut-off, every period. A worked example: the GC gives the owner a proper invoice on October 31. The owner's 28 days end November 28. If the owner pays, you are owed within 7 days of the GC being paid. If the owner does not pay, the GC must pay you by December 5, day 35, or give you a notice of non-payment before then. A bill you send November 3 goes on the November invoice instead, and all of those dates move about a month.
Progress billing vs final invoice
| Progress invoice | Final invoice | Holdback invoice | |
|---|---|---|---|
| When | Each billing period while work is under way | When your scope is complete | After the holdback period ends |
| Covers | Value of work done this period | Remaining contract value, plus approved changes | The amount retained |
| Holdback | Retained, as the contract provides | Retained | Released |
Billing your final invoice does not move your lien deadline. That runs from the day you finish or abandon the work (s. 41), not from your invoice date. See registering a lien and getting your holdback released.
How should holdback and GST be shown on the invoice?
The Act requires the owner to retain 10% of the value of work done and materials furnished (s. 18(1)), and says payments under Part 3 are subject to that retention (s. 32.1(2)). The Act does not set a format for showing holdback on a subcontractor's bill. GCs usually retain 10% from subs to match, and your subcontract sets that.
A common convention is to show the gross value of work this period, subtract the holdback, and show the net amount due, with a running total of holdback retained to date.
On GST, two rules are from the CRA:
- Alberta's rate is 5%.
- On a holdback required by law or a written construction contract, GST is collectible on the earlier of the day the holdback is paid and the day the holdback period expires, "even if you already issued an invoice and charged the GST/HST for the holdback amount" (RC4052).
Subs commonly charge GST on the net now and on the holdback at release, or on the gross. Agree one approach with the GC and your accountant. For an invoice of $500 or more, the CRA also wants your GST registration number, the GC's name, a description and the payment terms for the GC to claim the credit. See GST for subcontractors.
Example invoice layout
A plain-text template with each s. 32.1 item marked. The holdback and GST lines follow the convention above, not a legal format.
INVOICE This invoice is intended to be a
No. 2026-014 proper invoice under the Prompt
Payment and Construction Lien Act. [g]
FROM (contractor/subcontractor) [a]
Example Drywall Ltd.
123 Example Street SE, Calgary AB T2X 0X0
GST/HST no. 123456789RT0001
TO
Example General Contracting Inc.
Project: Unit 200 tenant improvement, 456 Example Ave SW, Calgary
INVOICE DATE: October 24, 2026 [b]
WORK PERIOD: September 25 to October 24, 2026 [b]
AUTHORITY: Subcontract No. SC-0317 dated August 12, 2026; [c]
Change Order CO-02 (written, approved October 6, 2026)
DESCRIPTION OF WORK [d]
Framing and board, levels 1-2, per SC-0317 Schedule A $18,000.00
CO-02: added bulkhead, corridor 2B $2,000.00
------------
Value of work this period $20,000.00
Less holdback retained (10%) -$2,000.00
------------
Net amount this period $18,000.00
GST 5% on net amount $900.00
------------
AMOUNT REQUESTED $18,900.00 [e]
CONTRACT SUMMARY
Subcontract value incl. approved changes $82,000.00
Billed to date (gross, incl. this invoice) $50,000.00
Holdback retained to date $5,000.00
PAYMENT TERMS [e]
Due under the Act and Subcontract SC-0317.
SEND PAYMENT TO [f]
Jane Example, Office Manager
accounts@example.ca, 403-555-0100
EFT details on file / cheques to the address above
The business, project and amounts are invented. Item [c] is the line people forget; the Act accepts a verbal contract if that is what you have.
Can a proper invoice be changed after it is sent?
Yes, if the parties agree to the revision, the date of the invoice is not changed, and it still contains every required item (s. 32.1(5)). Keeping the original date matters, because the clock runs from it.
What to do this week
- Ask the GC on each active job for its owner-billing date and its cut-off for sub invoices.
- Add the proper invoice statement and all seven items to your invoice template.
- Put the subcontract number and change order numbers on every invoice.
- Show holdback as its own line, with a running total retained to date.
- Start a log of your invoice date, the GC's owner-invoice date and the day you were paid.
Working commercial jobs around Calgary? Syndex is a free network where GCs send requests to the subcontractors in the trade they need. Join as a subcontractor.
Sources
- Prompt Payment and Construction Lien Act, RSA 2000, c P-26.4 (consolidated April 1, 2025)
- Prompt Payment and Adjudication Regulation, AR 23/2022 (consolidated November 26, 2025)
- Prompt Payment and Construction Lien Forms Regulation, AR 51/2002
- Prompt payment rules for construction industry, Government of Alberta
- Input tax credits, Canada Revenue Agency
- RC4052 GST/HST Information for the Home Construction Industry, Canada Revenue Agency
- GST/HST calculator and rates, Canada Revenue Agency
Last checked October 13, 2026.