With the Bank of Canada raising interest rates, it is likely that the CRA, either starting for the July quarter, but at the latest the October quarter will be increasing the prescribed rate for taxable benefits for employees and shareholders from interest-free and low-interest loans.
A history of this rate is as follows:
Q1-2007: 5%
Q2-2007: 5%
Q3-2007: 5%
Q4-2007: 5%
Q1-2008: 4%
Q2-2008: 4%
Q3-2008: 3%
Q4-2008: 3%
Q1-2009: 2%
Q2-2009: 1%
Q3-2009: 1%
Q4-2009: 1%
Q1-2010: 1%
Q2-2010: 1%
Q3-2010: Should be announced within a week.
The reason why this rate is significant is because issuing a low-interest rate loan is the easiest way to avoid income attribution. Just as an example, if you get your company to loan you money (which you would presumably use for investment purposes), you have to pay the company a 1% interest charge. You would deduct that amount from your income, while the company would include it as interest income on its side of the income statement. Also, spousal loans can be used to avoid income attribution.
While no matter what the rate is there is symmetry (i.e. one party can deduct what the other includes as income, assuming the loaned amount is used for income-generation purposes), higher rates discourage typically discourage borrowing to invest as typically it is the asset-rich entity that loans money out to the asset-poor (and presumably income-poor) entity in order to transfer income to a lower-rate person. If the prescribed interest rate is too high, the loanee will have to take on a higher amount of income at their (presumably) higher marginal rate.
There are rules with respect to the payment of shareholder loans (i.e. you must pay back the principal amount by the end of the following fiscal year or have it be a deemed dividend) but for loans between individuals, there is no duration rule with respect to the amount of interest to be paid – you can make a loan that will expire in 30 years at the rate of 1% for the purposes of the prescribed interest rate rules. Just make sure to document the loan and if there is any question as to the dating of the document, get it notarized or otherwise documented in case if the CRA comes knocking.