The GST/HST Return, known officially as Form GST34, is the primary sales tax filing that every registered business in Canada must submit to the Canada Revenue Agency (CRA) for each reporting period. The Goods and Services Tax (GST) is a 5% federal value-added tax imposed on most supplies of goods and services made in Canada, established under Part IX of the Excise Tax Act (R.S.C., 1985, c. E-15). In participating provinces — Ontario (13%), Nova Scotia, New Brunswick, Newfoundland and Labrador, and Prince Edward Island (all at 15%) — the federal GST is harmonized with the provincial sales tax into a single Harmonized Sales Tax (HST), which is also reported on this same return.

The Form GST34 requires registrants to report their total sales and other revenue (Line 101), the GST/HST collected or collectible on taxable supplies (Line 105), eligible purchases on which GST/HST was paid (Line 106), and the input tax credits (ITCs) being claimed to recover GST/HST paid on business inputs (Line 108). The difference between tax collected and ITCs claimed produces the net tax (Line 109) — a positive figure means the registrant owes tax to CRA, while a negative figure means the registrant is entitled to a refund.

Non-participating provinces maintain separate provincial sales taxes: British Columbia charges 7% PST under the Provincial Sales Tax Act (S.B.C. 2012, c. 35), Saskatchewan charges 6% PST under The Provincial Sales Tax Act (R.S.S. 1978, c. P-34.1), and Manitoba charges 7% RST under The Retail Sales Tax Act (C.C.S.M., c. R130). Quebec administers its 9.975% QST through Revenu Québec under the Act respecting the Québec sales tax (R.S.Q., c. T-0.1), not through CRA. These provincial taxes are not reported on Form GST34.

A GST/HST return must be filed by every person who is registered or required to be registered for GST/HST purposes. Registration is mandatory for any person making taxable supplies in Canada whose total taxable supplies (including those of associates) exceed $30,000 in any single calendar quarter or in four consecutive calendar quarters. Small suppliers below this threshold may voluntarily register to claim ITCs on their business purchases.

The filing frequency depends on the registrant's annual taxable supplies: businesses with annual taxable supplies of $1,500,000 or less may file annually; those between $1,500,001 and $6,000,000 must file quarterly; and those exceeding $6,000,000 must file monthly. The CRA assigns the reporting period at the time of registration, though registrants may request a change.

A return must be filed even if no revenue was earned or no tax was collected during the period — a nil return is required. Charities, public institutions, and financial institutions may have special reporting requirements. The due date for filing depends on the reporting period: annual filers have three months after their fiscal year-end; quarterly and monthly filers must file within one month after the end of each reporting period. Instalments are required for annual filers whose net tax for the prior year exceeded $3,000.

A complete GST/HST return requires accurate reporting of the registrant's legal name and 15-character business number (BN), which includes the RT program identifier assigned by CRA at registration. The reporting period start and end dates must match the registrant's assigned reporting period exactly. Total revenue reported on Line 101 must include all taxable supplies at the applicable GST/HST rate, zero-rated supplies (such as basic groceries and prescription drugs), and exempt supplies (such as residential rent, most health and dental services, and most financial services).

The GST/HST collected on Line 105 must reflect only the tax actually collected or collectible on taxable supplies — it should not include tax on zero-rated or exempt supplies. Input tax credits on Line 108 require supporting documentation: for purchases under $30 the supplier's name is sufficient; for purchases between $30 and $150 the registrant needs the supplier's name and BN plus the total amount including tax; for purchases over $150 full documentation including a description of the supply, the tax rate, and the purchaser's name is required.

Adjustments may include bad debt recoveries (section 231 of the Excise Tax Act), the GST/HST new housing rebate, the public service body rebate, or adjustments for the self-assessment of tax on imported taxable supplies. The certifier must be an authorized signing officer of the business and must certify that the return is correct, complete, and fully discloses all relevant information. Records must be retained for a minimum of six years from the end of the last tax year to which they relate, as required under section 286 of the Excise Tax Act.