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The fastest way to run short of cash in a young company is to spend money that was never yours. Sales tax you’ve collected and pay you’ve withheld belong to the CRA, and both come due on fixed dates whether or not your customers have paid you. To manage cash flow in a Canadian startup, treat those two piles as untouchable from the day they land.
Which tax payments drain your cash first?
Three of them, and they run on different clocks.
| Payment | When it’s due |
|---|---|
| GST/HST return, monthly or quarterly filer | One month after the reporting period ends |
| GST/HST return, annual filer | Three months after your fiscal year ends |
| Payroll remittance, regular remitter | The 15th of the following month |
| Payroll remittance, small new employer | Quarterly, 15 April, 15 July, 15 October, 15 January |
| Corporate tax instalments | Last day of each month, or each quarter if you qualify |
Corporate instalments only bite once you make a profit. Early on, the first two rows are the ones to plan around. The CRA assigns your GST/HST reporting period from your revenue, and you can ask to file more often. Filing more often is one way to stop tax money sitting in the account long enough to get spent.
Put the dates in a calendar the week you register. Nobody remembers “the 15th” in the middle of a product launch, and the CRA’s penalty clock doesn’t care that you were busy.
How much sales tax are you holding?
More than it feels like. Say an Ontario startup invoices $40,000 in a month. At 13% HST you’ve billed $5,200 of tax on top, and the customer’s cheque for $45,200 includes it. Only $40,000 is revenue. The GST/HST calculator splits any amount that way in a second.
Alberta would hold $2,000 (5% GST). Quebec would hold $5,990, since GST and QST together come to 14.975%. Same sale, very different pile to set aside. A registrant can claim back the GST/HST it paid on its own purchases, so what you actually send in is the difference, but you won’t know that number until you’ve added up the month.
Park the full tax amount in a separate savings account and move money out only on filing day. If a few bucks of interest land there, that’s a bonus, not a plan.
What does payroll do to your monthly cash?
Take two employees in Ontario, each paid $3,000 every two weeks. The payroll remittance estimate gives $961.03 per employee per pay period to send the CRA, so $1,922.06 for both. Your own share inside that is $456.83, the employer CPP and EI on top of the $6,000 in gross pay.
Spread over a month that’s about $4,164 to remit and about $13,990 of full payroll cost. That’s before rent, software or anyone’s coffee. If your sales run $40,000 and the tax piles above are set aside, payroll alone takes roughly a third of the real revenue.
Check each worker’s side on the take-home pay calculator before you promise a salary. A $78,000 wage doesn’t land in anyone’s account as $78,000.
How do you build a simple cash forecast?
A spreadsheet is enough. List the next thirteen weeks across the top. Underneath, put cash you expect to receive on the day you expect it, not the day you invoice, and every payment you must make on its due date. Subtract, carry the balance forward, and look for the first week it goes negative.
Picture Priya, who runs a small design software company in Waterloo. Her customers pay about 45 days after invoicing, yet payroll runs every second Friday. Her forecast showed a thin week six, well before anything felt tight. She moved a supplier payment by ten days and the dip disappeared. That’s all a forecast is for: spotting the squeeze while you can still do something about it.
Update it weekly. A forecast you check once a quarter is a history lesson.
Can borrowing fill a gap?
Sometimes, for a short one. A line of credit is built for timing gaps, such as waiting 45 days on an invoice. It’s the wrong tool for a gap that never closes. Run the interest through the line of credit calculator with your real balance before you rely on it, and use the rate on the offer in your hand. No lender rates are quoted here, because what a new company is offered depends on the lender and on you.
Late payroll money is the worst loan there is. The CRA penalty runs 3% for 1 to 3 days late, 5% for 4 to 5, 7% for 6 to 7 and 10% after that, with interest on top. On $4,164 that’s $416 for being a week and a day late.
Mistakes that hurt cash flow
Treating a signed contract as cash is the usual one. Revenue you’ve invoiced can’t pay wages until a customer pays. Close behind is mixing tax money into the operating account, because the balance then looks healthy on a day it isn’t.
A smaller one is forgetting that the estimates here are averages. The payroll figure is a yearly calculation divided by 26, and it leaves out workers’ compensation and other payroll levies. Your bookkeeping will show the true number.
And the tax bill on profit arrives eventually. If you’ve incorporated, the corporate tax calculator shows what a good year will cost.
Where the numbers come from
Due dates and penalties come from Canada Revenue Agency pages for GST/HST, payroll remitting and corporate instalments, read in September 2026. Sales tax rates and the payroll and pay figures come from this site’s calculators, which use 2026 data. The CRA pages don’t state every GST/HST reporting threshold, so check your assigned period in your CRA business account. This site is independent and not connected to the CRA or any government.
Frequently asked questions
Is the GST/HST I collect my money?
No. You hold it for the CRA until filing day. Keep it in a separate account so you don't spend it.
How often do I remit payroll deductions?
Most employers remit by the 15th of the following month. New small employers with monthly withholding under $1,000 may remit quarterly.
What happens if I remit payroll late?
The CRA charges 3% to 10% depending on days late, plus daily interest.
Do startups pay corporate tax instalments?
Only when there's tax to pay. Instalments are monthly, or quarterly for small qualifying Canadian-controlled private corporations.
Should I use a line of credit to cover a gap?
It suits short timing gaps. A gap that keeps growing needs a change in spending or sales, not more borrowing.
- Self-employed taxes in Canada: income, CPP and GST
How tax works when you are self-employed in Canada: reporting income and expenses, paying both halves of CPP, instalments and when to register for GST