The slips about you: T5018s from builders and GCs
When you sub on new builds or renovations, every contractor that pays you $500 or more in its reporting period files a T5018 about your company with the CRA. Two things about those slips cause trouble. The amounts usually include HST, so a year of slips can total 13% more than your actual revenue. And each payer reports on its own fiscal period, which rarely matches yours, so one slip can straddle two of your year-ends.
The CRA runs matching programs against this data. When the totals reported about you look larger than the revenue on your T2, a letter follows. We reconcile slip totals to the revenue ledger as part of the corporate tax filing and document the HST and timing differences, so the answer to that letter exists before anyone asks the question.
The slips you owe: paying your own subs
The duty runs the other way as well. If construction activities make up more than half of your business income and you pay subcontractors for construction services, a drain crew, an excavator, another plumbing shop taking your overflow, you must file T5018s for every sub paid $500 or more. You choose a calendar-year or fiscal-year reporting period, and the return is due six months after that period ends.
Each slip needs the sub's business number, which is far easier to collect with the first invoice than eleven months later. So we build sub onboarding into the routine: legal name, BN and a WSIB clearance certificate on file before the first payment. The clearance matters beyond good manners, because paying an unregistered sub in construction can leave your company carrying their WSIB premiums.
Holdbacks: billed now, taxed later
On contract work, Ontario's Construction Act lets the payer retain a 10% holdback until the lien period runs out. For income tax, held-back amounts are generally not income until they become legally receivable, which is usually when the lien period expires, not when you issued the invoice. HST follows the same logic: tax on the held-back portion is not collectible until the holdback is paid or becomes payable.
Handled deliberately, that is a legitimate deferral your filings should capture every year. The books recognize the full billing, the T2 adjusts for holdbacks not yet receivable, and the HST return holds back the matching 13%. Handled sloppily, a company pays tax a year early on money a builder still controls. The mirror image applies to holdbacks you retain from your own subs, so both sides of the ledger need the same discipline.
The calendar for an incorporated plumbing company
| Filing | When it lands |
|---|---|
| T2 corporate return | Six months after year-end; balance owing three months after year-end for most small CCPCs |
| HST return | Annual, quarterly or monthly by election and size; 13% applies to virtually all plumbing work |
| T5018 information return | Six months after your chosen reporting period ends |
| T4s for techs and apprentices | End of February, with source deductions remitted through the year |
| Corporate instalments | Monthly, or quarterly for eligible small CCPCs, once tax passes $3,000 |
| Owner and family T1s | April 30, or June 15 for the self-employed with any balance still due April 30 |
We run this as one calendar for the company and the household together, because the owner's T1, a spouse on payroll and the corporation's dividend decisions are one tax picture, not three. Personal tax filing for the family rides alongside the corporate work, and nothing is left to be remembered in the last week before a deadline.
When the CRA writes anyway
Construction sits high on the CRA's review lists: slip matching, HST refund verifications after a heavy equipment quarter, payroll exams looking at whether a helper was truly a subcontractor. A clean file usually ends these in one exchange of letters. When a review does open, our CRA Audit & Review Support service manages the correspondence and the deadlines, and because we reconciled the slips at filing time, the response is assembly rather than archaeology. That is the quiet payoff of doing the matching work up front, and it is why GTA builders keep asking their subs for accountant-prepared numbers.
