You should be filing your GST34, annual remittance report, (unless you have quarterly reporting) on which you will report all GST collected, and claim all GST paid, and either remit the difference or claim a refund. Once registered, you cannot "forget it" Once registered, if you have sales, you must collect GST by law. If you fail to do so, CRA will insist that you pay what you should have collected. If you do no business at all, you can still claim the GST on any expenses. If you do neither, you must file a nil return or CRA will assign arbitrary assessments and suggest that you should pay that.
If your accountant claimed the GST on your vehicle, you will be liable to re-pay the portion of GST that is equal to the GST on fair market value, if or when you close the business. The vehicle will be a deemed sale back to you due to change of use rules. GST/HST is a tricky business.
