interest rates don't directly affect the CAD. what they do affect is the capital and financial balance. if aust's IR is greater than that of overseas countries, then foreign capital will tend to flow into aust. this, however, carries with it servicing costs (eg. debt repayments, dividends) which will be recorded in the net income category in the current account balance, most likely as a deficit. if aust's IR is lower than the rest of the world, the opposite happens, and net income will tend to be in surplus. therefore, if the RBA raises IR in aust, the CAD will likely worsen, ceteris paribus. on the other hand, if the RBA lowers IR in aust, then the CAD will likely improve. of course, IR also has many other indirect effects on the economy, such as economic growth, and the level of investment, which could and do affect the CAD to some extent