Anonymised, illustrative composite. A Nova Scotia mechanical contractor stood up a maintenance and service division alongside its project work, priced it on instinct, and let two problems build at once.
At a glance
The division started as an accommodation to a few good project clients who wanted ongoing maintenance, priced at a round $85 an hour because nobody had costed it properly. It grew fast — fast enough that, without anyone deciding to, it crossed two lines in the same stretch of months.
The first line was internal: a cost study assigning technician wages, van costs, tooling and a fair share of dispatch overhead to the service hour found a fully loaded cost of $97/hour against a billed rate of $85/hour — every hour billed was losing $12. The second line was statutory: under the Excise Tax Act s.148(1)(b), a business stops qualifying as a “small supplier” once its revenue exceeds $30,000 measured over the four preceding calendar quarters, at which point it must register and start charging GST under s.165(1)’s 5% rate plus the applicable provincial component.
Quarterly service revenue ran $6,200, then $7,900, then $8,400, then $9,100 — a trailing four-quarter total of $22,500 at the end of the third quarter, comfortably under the $30,000 line, then $31,600 by the end of the fourth. The division crossed the small-supplier threshold in the same quarter the cost study landed on the desk.
At the old $85 rate and roughly 1,400 annual service hours, the $12/hour shortfall was costing the division about $16,800 a year before anyone corrected it. Repricing to $115/hour turned that same volume into roughly $25,200 of additional annual margin — an $18/hour swing on 1,400 hours.
Two separate rules, one repricing exercise. The cost study set the floor the new rate had to clear — below $97/hour the division was paying to work. The ETA threshold set a second, independent obligation that had nothing to do with profitability: once trailing four-quarter revenue passed $30,000, registration and GST/HST collection stopped being optional. A rate built only to cover cost, with no allowance for the tax the division was now required to charge and remit, would have understated what clients actually needed to be billed from that point forward. The rate the province actually required by then had itself just moved: Nova Scotia’s HST dropped from 15% to 14% on April 1, 2025, when the province cut its own portion from 10% to 9%, so the tax the division had to collect and remit on every post-registration invoice was 14% of the billed amount, not the 15% an older invoice template might still assume.
The division moved to $115/hour, registered for GST/HST once the trailing-quarter total confirmed it had exceeded the small-supplier threshold, and began charging tax on invoices going forward. On the tax mechanics behind the second half of that decision, see how HST works on construction contracts. The related job-costing discipline that caught the first half is in how a job costing rebuild exposed unbilled shop overhead and how margin fade got traced to two specific cost codes.
Had the division kept billing at $85/hour past the point its trailing four-quarter revenue crossed $30,000, it would have been operating as an unregistered supplier required to charge and remit GST/HST it was not collecting — an exposure entirely independent of the $12/hour the rate was already losing on cost. Fixing the rate without checking the threshold would have solved one problem and left the other running.
Track trailing four-quarter revenue for any new service line on a rolling basis, the same way the ETA measures it — not by calendar year, not by fiscal year, but as a moving four-quarter total that can cross $30,000 mid-quarter without any single quarter looking large on its own: $6,200 + $7,900 + $8,400 + $9,100 is $31,600. No individual quarter looked alarming; the rolling total did.
The cost study and the small-supplier threshold are entirely independent triggers that simply landed close together: nothing about crossing $30,000 in trailing revenue caused the $12/hour shortfall, and nothing about the shortfall caused the threshold to be crossed. Fixing only the rate, without checking the ETA position, would have left the division billing an under-registered, under-taxed rate; fixing only the registration, without checking the cost study, would have left it charging GST correctly on a rate that was still losing $12 an hour. The firm now reviews both checks — a margin test and a rolling-revenue test — on the same quarterly cadence for any new service line, specifically because this case showed the two can cross their own thresholds independently and close together.
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