Q1 GST Filing Guide for Alberta Businesses

If your Calgary business files GST quarterly, your Q1 2026 return (covering January through March) is due by April 30, 2026. Here's a complete guide to filing accurately and on time.

Step 1: Reconcile Your Sales

Before preparing your GST return, ensure all revenue for January through March is recorded in your accounting software. Reconcile your bank deposits against your recorded sales to verify nothing is missing. Pay special attention to any cash transactions, which are easy to overlook.

Step 2: Verify GST Collected

Run a GST report in your accounting software for the Q1 period. Verify that 5% GST has been applied to all taxable sales. Common errors include: forgetting to charge GST on new revenue streams, incorrectly zero-rating domestic sales, or double-counting GST on returns and credits.

Step 3: Calculate Input Tax Credits

Input Tax Credits (ITCs) are the GST you paid on business purchases that you can claim back. Review your expenses for Q1 and ensure all GST paid is captured. Common ITC categories include: office supplies, professional fees, advertising, equipment purchases, and subcontractor invoices that include GST.

Step 4: Calculate Net GST

Your net GST is simple: GST collected minus ITCs claimed. If the result is positive, you owe CRA. If negative (meaning you paid more GST on purchases than you collected on sales), you'll receive a refund.

Step 5: File and Remit

File your GST return through CRA My Business Account or through your accounting software (QBO supports direct filing). If you owe a balance, remit payment by April 30 to avoid penalties and interest.

Common Q1 Mistakes

• Forgetting to include cash sales
• Not claiming ITCs on year-end accounting fees (often invoiced in Q1)
• Missing ITCs on annual subscriptions renewed in January
• Incorrect treatment of bad debts (you can recover GST remitted on uncollectible invoices)

Let Castle File for You

GST filing is included in all of Castle Bookkeeping's monthly plans. We calculate, prepare, and file your return so you never miss a deadline. Contact us to learn more.