Canadian GAAP is converting to IFRS in 2011.
As of now, with Canadian GAAP, goodwill is tested for impairment and not amortized. IFRS also tests for impairment and does not amortize each year. There is not really much difference. There are only small tweaks not really worth getting into in where the two differ, in how the impairment steps take place. But basically, CICA 3064 is converging with IAS 36 & 38. This is for Canadian companies. I have never had the need to learn the current tax characteristics of Canadian Income Trusts in their current form (just regular Canadian companies), so i have never bothered to study CA income trusts under CA GAAP, let alone under IRFS. So their may be some differences with respect specifically to CA income trusts, which i'd be happy to look up at a later date for you.
Over here in the US (using US GAAP), goodwill (and certain other intangible assets) are also impaired, according to the rules in SFAS 142. It's now annually tested for impairment in a 2 step process. Where, basically, the company just estimates the fair value of each reporting unit to which goodwill is attributed and compares that estimated fair value with the carrying amount of the reported unit. Any excess of the carrying amount over the estimated fair value must be recognized as an impairment loss up to the amount of the goodwill. This rule became effective around 2002.
There is no tax effect, or any real cash effect. It is really a non-event. The only effect is that it will dramatically effect reported earnings in the year of impairment, as the impairment decreases net income dramatically in a given year. Moving forward though, this impairment "clears the books", and the company will report higher earnings than it would if they were still amortizing, and higher ROA, ROE, P/E because of the switch from amortization to impairment. It's just your typical "Big Bath" accounting.
Some intangibles are still amortized annually. Amortization of intangible assets may be based on useful lives as defined by law (e.g. patents) or regulation, or such assets may be depreciated over teh period during which the firm expects to receive benefits from them, like computer software. Companies can use either straight-line or units of production methods.