You have to pay attention to various sets of ground rules when you file your tax return. You rely on what our tax laws say, the Canada Revenue Agency's take on those laws and the tax court's interpretations of those same laws.

The CRA does a decent job in stating its position by publishing tons of helpful guides, booklets and tax tips. These documents are generally supported by tax court's interpretations.

This transparency allows you to decide if the CRA is playing fair.

Understandably, it is more difficult to determine if taxpayers use reason when filing their tax returns because a tax return is a private document. Nonetheless, tax court cases provide a glimpse of how certain taxpayers push the limit by claiming conspicuous expenses, how the CRA react and where the tax court draws the line.

In a recent case, Dilys Massicotte vs. The Queen, Nov. 27, 2009, the taxpayer claimed a certain rental expense.

The expense is question were amounts paid to the taxpayer's two young teenager sons - aged 12 and 14 - to perform maintenance and cleanup work at her rental property during 2004 and 2005.

The taxpayer paid $7,500 to each of her sons per year. The total amount of $15,000 exceeded her annual gross rent. The rental loss for those two years also exceeded $15,000. The CRA disallowed the $15,000 expense for those two years.

The judge acknowledged the taxpayer had tenant problems. The city had issued infraction notices regarding the property's poor upkeep and non-removal of snow from the sidewalks. A tenant was evicted in 2004 and left her possessions behind. Removing her contents required multiple trips to the dump. The eviction's aftermath also required extensive cleaning, repairing and refinishing of the floors.

The taxpayer paid her sons $12 per hour during those two years. The judge noted that amounted to 13 hours of work every weekend per child. In reality, the working weekend's hours had to be longer than 13 hours after discounting certain non-work weekends due to birthdays, special occasions and hockey practices. The children did not work during the weekdays.

The rental property was situated about 30 to 35 kilometres from the taxpayer's home which would have required the taxpayer to drive. The taxpayer claimed this travel time as working hours for the children.

The judge mused that the $12 per hour rate was on the high side and wondered if the paid travel time was reasonable for local work. In the end, he ruled the taxpayer did not provide him with enough evidence to show how each child could have worked more than 13 hours per weekend during those two years.

He acknowledged the children did provide valuable services and allowed a flat deduction of $500 per child for each of those two years.

Here is an enduring lesson from this and other similar tax court cases; you also have to pay attention to your exuberance when filing your tax return or be prepared to face a judge who, more likely than not, will temper your enthusiasm.