Automate the assembly, the numbering, the sending and the chasing. Keep a person on the release — because in Ontario a compliant construction invoice starts a statutory clock, and because what your invoice must contain is prescribed by regulation.
Key takeaways
Ask a contractor why invoices go out late and almost nobody says "typing takes too long". They say the timesheets were not approved, or the site meeting to agree progress did not happen, or nobody was sure whether the extra work had been accepted. Those are input problems. Automating the document while leaving the inputs broken produces a faster route to an invoice you cannot send.
So automating invoicing properly means automating three separate things in order: the readiness of the inputs, the assembly of the document, and the follow-up. Only the middle one is about templates.
For time-and-materials work, the input is approved hours and material costs. Field time tools exist for this — Procore's project timesheets documentation covers creating and approving timesheets on web and mobile, and its Timecard tool documents specifying billable hours on projects and exporting or filtering by date, employee, project and billable status. If billable hours are captured and approved daily, a T&M invoice is generated, not assembled.
For progress billing, the input is an agreed percentage of completion. That agreement is a site conversation. What automation can do is make sure the conversation happens on a fixed date, that the schedule of values is already in the system, and that the draft application is waiting when the walk finishes. Procore's invoicing documentation illustrates the general pattern of owner and subcontractor invoices generated against contract line items rather than typed fresh.
Your customer's ability to claim an input tax credit on your invoice depends on what is printed on it, and that is prescribed rather than conventional. Paragraph 169(4)(a) of the Excise Tax Act makes the credit conditional on the recipient obtaining prescribed information, and section 3 of the Input Tax Credit Information (GST/HST) Regulations sets it out by size of the total amount:
Prescribed information, by invoice total
Under $100: supplier's (or intermediary's) name or business name; the invoice date, or the date tax became payable where no invoice is issued; and the total amount paid or payable.
$100 to under $500: the above, plus the registration number assigned to the supplier or intermediary under section 241 of the Act, plus the amount of tax — with an indication of status where supplies of different status appear on the same document.
$500 or more: the above, plus the recipient's name or business name (or a duly authorised agent's or representative's), the terms of payment, and a description of each supply sufficient to identify it.
Two things follow for template design. Your GST/HST registration number belongs on the template permanently — our sister firm addresses the common question of whether your HST number goes on every invoice. And "description of each supply sufficient to identify it" rules out the one-line invoice that says "work performed". A generated description drawn from the schedule of values or the approved timesheet lines satisfies it; "as per contract" does not.
Outside construction, an invoice is a request for payment. On an Ontario construction project it can be more than that: an invoice meeting the statutory requirements triggers payment timing under the Construction Act. Our sister firm sets out the mechanics in prompt payment rules and deadlines and answers the short version in this note on prompt payment under the Construction Act.
The practical consequence is that a scheduled invoice which fires automatically on the 25th with the wrong figures is not a clerical annoyance to be corrected next month — it interacts with a statutory scheme, and correcting it may have its own consequences. Build the automation to prepare and queue, with a named person releasing. The saved time is in the preparation, and you lose almost none of it by keeping a human on the button.
Holdback deserves its own line on the invoice and its own treatment in the ledger, because it is a statutory withholding rather than a discount — see what owners must withhold. An invoicing template that nets holdback silently into the total makes both parties' records harder to reconcile at release.
Reminder sequences are the least controversial automation in this article and often the highest-return: a polite note the day after terms expire, a second a week later, a third that copies the person who signed the contract. Language models are useful for drafting these in a tone that does not damage the relationship, and for summarising a long email thread into "what is actually being disputed" before you reply.
Where the line sits: a reminder is a communication; escalation is a decision with legal consequences. Suspending work, registering a lien, or starting a claim are choices a person makes with advice. Our sister firm covers the practical route for suing a customer for an unpaid invoice in Ontario, and the timing question that catches contractors out in how long you have to register a lien. Deadlines run from events on the job; no reminder sequence should be the only thing watching them.
Issued invoices are records. Under section 286 of the Excise Tax Act, records must be kept in Canada in English or in French unless the Minister authorises otherwise (subsection 286(1.2)), retained for six years after the end of the year to which they relate (subsection 286(3)), and kept in an electronically readable format for that period where they are kept electronically (subsection 286(3.1)). Paragraph 230(4)(b) of the Income Tax Act imposes a matching six-year rule on the income tax side. If your invoicing lives in a subscription tool, confirm the export before you rely on it.
A six-person electrical contractor, illustrative
Before. Invoicing happened on the last Saturday of the month, from paper timesheets and memory. Descriptions were vague, extras were argued about, and two customers routinely paid sixty days out because the invoice arrived three weeks after the work.
Change one — inputs. Hours captured on phones daily against a job and approved by the foreman each morning for the previous day. Material invoices captured on arrival and coded to the job.
Change two — assembly. Drafts generated weekly from approved hours and coded materials, each line describing the work sufficiently to identify it, holdback shown separately, registration number on the template.
Change three — release. The owner reviews and releases in about ten minutes a week. Nothing sends itself.
Change four — follow-up. A three-step reminder sequence that stops the moment payment arrives or the customer replies. Disputes go to a person immediately.
The real gain. Not the time saved drafting. It is that the extras are billed while the customer still remembers agreeing to them.
For repeating service contracts with fixed monthly amounts, that is reasonable. For progress billing and time-and-materials on construction projects, prepare automatically and release manually — the interaction with statutory payment timing makes an unreviewed send a poor trade for the minute it saves.
A description of the supply sufficient to identify it, and the GST/HST registration number on smaller invoices where people assume it is unnecessary. The regulation's tiers make the registration number a requirement from $100 upwards.
Drafting them is a good use. Read them before they go, particularly the third one — the tone that gets a cheque from a long-standing customer is not the tone a model defaults to, and the relationship is usually worth more than the invoice.
The same prescribed-information tiers apply to your ability to claim the credit, so build the check into intake rather than discovering a missing registration number at filing. Payment obligations down the chain are a separate question — see subcontractor lien rights when the general contractor has not been paid.
A 30-minute call is enough to tell you whether AI pays for itself here.
