GST/HST and CRA registration for Canadian deck contractors explained

What to take away

Small supplier thresholds and when CRA registration becomes mandatory

The Canada Revenue Agency measures your revenue, not your profit. For GST/HST purposes, you look at your taxable supplies from Canadian customers over the last four consecutive calendar quarters. Once that total passes $30,000, you stop being a small supplier and must register.

There is a second trigger that catches growing deck and patio businesses off guard. If you exceed the threshold in a single calendar quarter, you must register and start charging within a short window rather than waiting for the four-quarter test to catch up.

The CRA sets out when to register for and start charging the GST/HST, including the timing rules for partnerships and incorporated companies.

Revenue counts when it becomes payable, not when cash lands in your account. A deposit taken in March for a June deck build usually counts in the quarter it was invoiced. That timing difference is why a strong season can push you over the line mid-year.

Sales of your own used business equipment, zero-rated exports and most insurance proceeds sit outside the calculation. Residential deck work in Canada is taxable, so nearly every job you quote adds to the running total.

A sole proprietor building three decks a year at $18,000 each crosses $30,000 in the second quarter of the season. Registration is not optional at that point, and charging tax on the next signed contract is expected.

If you are still deciding how to structure the business before registration, the startup costs breakdown covers the accounts and registrations that come first.

Registering for a GST/HST number and managing the business account

Registration happens through the CRA's Business Registration Online service, by phone, or through a representative with the right authorization. You need your social insurance number or business number, your legal name, your address and a description of what you sell.

The CRA issues one business number with programme accounts attached. Your GST/HST account appears as RT0001 after the nine-digit root. A payroll account is RP0001 and a corporate income tax account is RC0001. Quote the full number with the letters on invoices and correspondence.

Reporting periods run monthly, quarterly or annually. Most new registrants with modest revenue are assigned quarterly filing, while larger operations file monthly. You can ask to change your period if seasonal cash flow makes one option easier than another.

Keep the account details current. Address changes, ownership changes and a switch from sole proprietor to corporation all affect the account. A corporation is a separate taxpayer and needs its own registration, even if the same person owns it.

Which GST/HST rate applies in each province for deck patio contractors

The rate you charge depends on where the work happens and, for some services, where the customer is. The rate is set by the province where the work sits, not the province of the contractor's mailing address. The CRA publishes which rate to charge and collect on a contractor invoice.

Ontario contractors charge 13% HST on a deck build and remit the federal portion through their GST/HST return. Quebec is different: you register for GST with the CRA and for QST with Revenu Quebec, then file two returns. Contractors working across a provincial border need to track which rate applies to each job.

British Columbia, Saskatchewan and Manitoba charge GST plus a provincial sales tax, but the PST or RST generally applies to goods rather than to construction services. That distinction matters when you supply both labour and materials, because the tax treatment of each line can differ.

Input tax credits on materials, tools and subcontractor invoices

An input tax credit lets you recover the GST/HST you paid on purchases used in your commercial activity. Deck builders claim them on lumber, composite boards, fasteners, concrete, railing systems and the small tools consumed on site.

Input tax credits on materials and subcontractor invoices usually go unclaimed because receipts were never filed, not because the purchase was ineligible.

You need a valid invoice showing the supplier's GST/HST number, the amount of tax and the date. A till receipt without those details will not support a claim. Keep supplier invoices with the job file so the credit ties back to a specific build.

Larger purchases follow the same logic. A new mitre saw, a compactor or a truck used only for business generates an input tax credit on the tax paid. Vehicles have extra rules, so confirm the capital property treatment before claiming the full amount.

Subcontractor invoices matter too. When you hire a framing crew or a railing installer who is registered, they charge you GST/HST and you claim it back. If they are not registered, no tax is charged and there is nothing to recover.

Use the CRA guidance on how to calculate and report the GST/HST to work through a return line by line and confirm which credits belong in the period.

Invoicing rules, deposits and progress billing on deck builds

A GST/HST invoice needs the supplier's name and business number, the date, a description of the work, the amount charged and the tax shown separately. For jobs over $30,000, the CRA expects the customer's name and the terms of payment as well.

Deposits are taxable when you receive them if they are applied to a future supply. A $5,000 deposit on a $40,000 deck build carries tax at the applicable rate at the time it is taken. Show the deposit and the tax on the invoice so the customer can see what was charged.

Progress billing follows the same principle. Each draw is a supply of services to the extent the work is done, so tax applies to the amount billed, not to the whole contract at once. Holdback amounts under a construction contract are usually taxed when they become payable.

A clear invoice reduces disputes and makes the return easier to prepare. A quote template that separates labour, materials and tax from the start keeps the paperwork consistent across every build.

Filing, remitting and the penalties that follow late returns

Your return is due based on the reporting period the CRA assigns. Monthly filers file one month after the period ends, quarterly filers file one month after the quarter, and annual filers generally file three months after their fiscal year end. Payment is due at the same time as the return for most filers.

If you owe tax and file late, the CRA applies a penalty based on a percentage of the balance owing plus additional amounts for repeated failures. Interest accrues on the unpaid balance from the due date.

The CRA's page on GST/HST filing penalties explains how the penalty is calculated and when it applies.

A nil return is still a return. Contractors who stop working for a season, or who have no tax to remit in a period, must file on time to avoid the failure-to-file penalty. Setting a reminder for each period is cheaper than paying the charge.

Filing online through My Business Account or a certified software package confirms receipt and reduces processing errors. Keep the confirmation number with your records in case the CRA asks for proof later.

Rebates, confirming account numbers and vetting subcontractors

Some purchases do not generate a straightforward input tax credit but may qualify for a rebate instead. The CRA's rebate programme covers specific situations, including certain expenses for businesses and public service bodies.

Before you claim anything, confirm the supplier's GST/HST number. A number that does not match the business name on the invoice is a warning sign, and the CRA can deny the credit if the supplier was not registered. Check new suppliers before the first invoice, not after.

Subcontractor vetting protects you twice. You avoid paying tax to someone who is not registered, and you avoid the risk that a worker is really an employee. Misclassification affects payroll, source deductions and your compliance checklist for the year.

Ask every subcontractor for a clearance letter or a copy of their registration confirmation. Keep it in the vendor file with their insurance and workplace safety documentation. That habit pays off during a CRA review or a provincial audit.

Bookkeeping habits that keep GST/HST clean all season

Separate your GST/HST money from operating cash the moment it lands. The tax you collect is not yours, and a busy July can leave you short in October if it was spent on materials.

Costly GST/HST mistakes rarely surface in the same quarter. They surface at a CRA review, a business sale, or a cash-flow crunch.

Reconcile the GST/HST account every month against your sales records. A quick check catches missing invoices, duplicate entries and jobs billed at the wrong rate before they reach a return. Good deck and patio hiring habits make the quarterly filing a short task rather than a rebuild.

Photograph supplier invoices on site and file them against the job number the same day. Paper receipts fade, and a lost invoice means a lost input tax credit. A simple folder structure by month and supplier is enough.

Review your pricing once a year with tax in mind. Contractors who quote round numbers and absorb the tax quietly lose margin on every job. Getting pricing and profit right means the tax is visible on the quote and the customer understands what they are paying.

Set aside time in the off-season to review the year. Confirm your reporting period, check that your account details are current, and reconcile the returns you filed against your bank deposits. That review is the cheapest audit preparation available.

The single habit that prevents most errors is holding the tax collected in a separate account from the day it is charged.

Common questions