GST/HST Rounding: Why Canadian Vendor Bills Land a Cent Off

Canadian vendor bills often land a cent off because the vendor rounds GST/HST on each line and adds the results, while most accounting systems calculate tax once on the subtotal. Both methods are allowed, so neither side is wrong.

The fix is to record the tax exactly as the vendor charged it, line by line, and split it into what you can recover and what becomes cost. MakersHub is set up around how your business already works, and our team configures it with you.

Charley Howe, our co-founder and President, put the cost of those pennies plainly:

Here is why the two methods differ, what that looks like on a real bill, why one cent matters at tax time and in job costs, and how to fix it.

Why do the vendor and the accounting system both get it right?

Because the Canada Revenue Agency (CRA) allows both. Its general guide for GST/HST registrants says to round GST/HST to the nearest cent: down if the fraction is less than half a cent, up if it is half a cent or more. It then says that when a customer buys more than one item at the same rate, the seller can add up the prices, calculate the tax on the total, and round once.

So a vendor can round each line and add the results, or add the lines and round once. Each method is correct. They just don't always produce the same number. When the vendor rounds per line and your accounting system rounds the subtotal, the tax on the bill and the tax in your books can differ by a cent, sometimes two, and the difference changes from bill to bill.

One bill like that is nothing. A supplier that sends a few hundred bills a month turns it into a standing job, because every bill has to be checked and every difference trued up before the books close.

What does a one-cent difference look like on a real bill?

Take a three-line bill from a British Columbia supplier. BC charges 5% federal GST and 7% provincial sales tax (PST). Here is the vendor's math, line by line, against the accounting system's math on the subtotal:

Look at the bottom line. Both versions total $129.37, so the bill ties out and nobody notices. But the GST is a cent higher on the vendor's bill and the PST is a cent lower. If your system recalculates, your books record one cent less GST than you actually paid and one cent more PST.

This is the version that slips past everyone. When the total matches, the split between the two taxes can still be wrong, and the split is the part that matters. One tax comes back to you. The other doesn't.

Why does a cent matter if the bill still ties out?

Because GST/HST and provincial sales tax end up in different places. Registered businesses recover the GST/HST they pay on business purchases by claiming input tax credits (ITCs), a credit against the tax they collect. The CRA's input tax credit page is explicit that this includes HST paid in a participating province. To support the claim, the CRA's registrant guide (RC4022) lists what the supplier's invoice must show. For a purchase of $100 or more, that includes the total GST/HST charged and the supplier's GST/HST registration number.

PST works the other way. PwC's summary of Canadian sales taxes describes PST in British Columbia, Saskatchewan and Manitoba as a retail sales tax, not a value-added tax, and not recoverable. When a business pays PST on a purchase, it generally cannot claim it back, and the tax becomes part of the purchase cost. For a contractor, that means PST belongs in job cost.

Put those together and the one-cent problem has two sides. GST recorded a cent short understates the credit you can claim. PST recorded a cent high overstates the cost of the job. Neither is material on one bill. Across hundreds of bills a month, the totals stop matching your vendor statements, and someone has to reconcile them by hand.

That is exactly what Foster Heating & Cooling, an HVAC contractor on Vancouver Island, was living with. Its largest supplier calculates tax line by line, and QuickBooks Desktop calculates it on the subtotal. Across 200 to 300 bills a month, each bill landed a cent or two off on both GST and PST. Someone had to find and true up every difference by hand. The full story is in the Foster Heating & Cooling customer story.

What about bills where the tax is included in the price?

Some vendors don't show tax as a separate line at all. The CRA allows that: for purchases of $100 or more, its ITC chart accepts either the total GST/HST charged or a statement that the amount paid includes the GST/HST at the applicable rate. Fuel receipts, small-tool purchases and some subcontractor bills often arrive this way.

To claim the credit, the tax has to be backed out of the price. At the 5% GST rate, the tax inside a tax-included amount is 5/105 of it. On a $73.50 purchase that is $3.50, and the pre-tax amount is $70.00. In a 13% HST province the fraction is 13/113. Backing tax out has its own rounding, so a tax-included bill can land a cent away from the same purchase invoiced with tax shown separately.

The practical rule is the same as for line-by-line bills. Record what the document supports, keep the invoice with it, and don't let a recalculation quietly replace the vendor's number. If a supplier sends both kinds of bills, ask it to show tax separately. Separate tax lines make the credit easier to support and the reconciliation easier to finish.

Which Canadian sales taxes can you recover?

Charley's post sums up the split as recoverable GST one way and provincial tax the other. The exact line depends on the province, because provinces handle sales tax in three different ways:

Rates and recovery rules are from PwC's Canadian tax summary, the CRA, and Revenu Québec's GST and QST rate table. Quebec's QST is administered by Revenu Québec rather than the CRA, and Manitoba calls its provincial tax retail sales tax (RST). A tool that only knows the word “PST” will miss both. Specific purchases can have their own rules, so confirm unusual items with your accountant.

Why do hardcoded tax tables break?

Because rates change. On April 1, 2025, Nova Scotia cut its portion of the HST by one percentage point, taking the combined rate from 15% to 14%. Any AP tool carrying its own table of Canadian rates had to wait for its software provider to update it, on the provider's schedule. Until it was, every Nova Scotia bill was coded at the wrong rate.

Your accounting system already holds your tax codes, set up the way your accountant wants them, and it gets updated when rates change. If you pull tax codes from there instead of from a table inside the AP tool, you only have one set of codes to keep current. MakersHub pulls tax codes and rates directly from QuickBooks Online and applies them at the line level. On QuickBooks Desktop, the same pull runs through the Web Connector, Intuit's tool for syncing outside software with Desktop.

How does MakersHub handle Canadian sales tax?

It reads the bill the way the vendor wrote it. WiseVision, MakersHub's bill-reading AI, captures every line item rather than only the total, so the tax on each line is recorded as charged rather than recalculated. Where the vendor's line-by-line math disagrees with your accounting system's subtotal rounding, MakersHub flags the difference and trues it up, instead of leaving someone to find it at month-end.

Each line is then coded with the tax codes from your own accounting system. Recoverable tax lands on the recoverable side, and non-recoverable provincial tax lands in the job, the way your codes are set up. You set your coding rules once, and MakersHub applies them everywhere. That includes vendor-specific exceptions, such as a supplier whose items are PST-exempt for your business. MakersHub's line-level automated coding does the work that used to take a person with a calculator.

MakersHub is transparent about where every bill sits and who is holding it, so anyone reviewing a Canadian bill can see the tax on each line and how it was coded. Approvers use MakersHub without training. They approve from email in one click, and see only the bills that are theirs.

Charley's post ends with an offer, and it stands: if your Canadian AP has a number that never quite matches, tell us what it is. We will tell you plainly whether MakersHub catches it today.

How can you fix the penny problem without new software?

You can shrink it by hand, and some teams should start here:

These help. They also all rely on someone remembering to do them on every bill, which is the part that breaks at a few hundred bills a month.

When does the rounding difference not matter?

If your vendors calculate tax on the invoice total, the way most accounting systems do, the two methods agree and there is nothing to reconcile. The same is true if you operate only in Alberta or the territories, where GST is a single 5%, and your bill volume is low enough that a stray cent is easy to spot and fix. The problem grows with three things: vendors that round per line, provinces with two separate taxes, and volume. Plenty of Canadian contractors and distributors have all three.

For a broader look at AP tools in Canada, see our guide to AP automation software for Canadian businesses. Charley wrote earlier about the Ontario contractor that waited eight years for Canadian tax support, and our accounting system integration hub lists every system MakersHub syncs with.

Frequently asked questions

Why is GST/HST on a vendor bill a cent different from my accounting system?

Because the CRA allows tax to be rounded either on each line or once on the total, and the two methods can produce different results. The vendor often rounds per line and the accounting system rounds the subtotal. MakersHub records the tax line by line as the vendor charged it and trues up the difference against your accounting system.

Is it wrong for a vendor to calculate GST/HST on each line?

No. The CRA's guidance for registrants allows rounding each amount to the nearest cent, and also allows adding up items taxed at the same rate and rounding once. Both are correct. MakersHub handles either, because it reads the tax the vendor actually charged.

Can a business recover provincial sales tax in Canada?

It depends on the province. HST, including its provincial portion, is recoverable through input tax credits, and Quebec's QST is generally recoverable through input tax refunds. PST in British Columbia and Saskatchewan and RST in Manitoba are not recoverable and become part of the cost. MakersHub codes each line with your own tax codes, so the recoverable and non-recoverable portions land where your codes send them.

What does a supplier invoice need to show to support an input tax credit?

For purchases of $100 or more, the CRA requires an indication of the GST/HST charged and the supplier's GST/HST registration number, along with the supplier's name, date and total, and purchases of $500 or more need more detail. MakersHub captures the full invoice, not just the total, so that information stays attached to the bill.

Why shouldn't AP software use its own table of Canadian tax rates?

Rates change, as Nova Scotia's did on April 1, 2025, and a built-in table is only as current as the software vendor's last update. MakersHub pulls tax codes and rates from your own accounting system, so there is one source of truth to maintain.

Does MakersHub work with QuickBooks Desktop in Canada?

Yes, through the Web Connector. MakersHub also syncs with QuickBooks Online, NetSuite, Sage Intacct, Xero and Intuit Enterprise Suite, and Smart Data Connect covers other accounting systems. On QuickBooks, tax codes come straight from your company file.

A cent is the smallest number in your books and one of the most expensive to chase. We built MakersHub to record Canadian tax exactly as the vendor charged it, so your team stops chasing it by hand. If there is a number in your Canadian AP you are still reconciling every month, tell us what it is. Get started with MakersHub.

Sources: Canada Revenue Agency, General Information for GST/HST Registrants (RC4022) and Input tax credits; PwC Worldwide Tax Summaries, Canada: Corporate, Other taxes (reviewed June 2026); Government of Nova Scotia, Finance and Treasury Board news release, March 31, 2025; Revenu Québec, Tables of GST and QST Rates; MakersHub published customer stories. Worked example calculated by MakersHub.