Well, each business venture needs to be evaluated on its own circumstances and what applies to your own business, if applied to another could get that business in a lot of trouble. I agree with Ivana though, a turnover of nearly $20k would be pushing the limits, I do know of a number of ventures, such as some types of racing, which have high turnover, but are not likly to turn a profit, so are classed as a hobby.

If in doubt I would always get a ruling from the ATO rather than just rely on one accountants opinion.