But isn't the Tax Office cracking down on expense claims? Work-related expenses are one of the big-ticket items in tax returns, so they come under scrutiny every year. Last year, according to the Tax Office's figures, 7.6 million people claimed work expenses in their tax return, with the average claim totalling $1920. The most common claims were for car, travel, uniform and self-education expenses.

In a recent speech, the second commissioner of taxation, Jennie Granger, said the regulator was particularly concerned people might be tempted to inflate their claims in difficult times, so work-related expenses would be under the spotlight again this year. But that's no reason not to claim legitimate expenses.

What can I claim? You can claim any expenses you incurred in relation to your employment. That's a broad brief but the Tax Office says there are some general rules to keep in mind. First, you must have incurred the expense in the year you are claiming it. You can't claim for past years (though you can apply to amend those tax returns) or claim expenses incurred after June 30 in this year's return. The expense must be work-related and not private. If the expense has been reimbursed by your employer, you can't double-dip and claim it in your own return. If you have received an allowance from your employer, it does not automatically entitle you to a deduction. You must still prove the expense was incurred by you and was work-related. You must also keep written evidence of your claims if they total more than $300.

Does that mean I can automatically claim $300? Hmm. The Tax Office may ask you to justify how you worked out your claim, so you can't just put in an automatic claim. If your total expenses are more than $300, you'll also need records to justify the entire amount not just the amount over $300. Your evidence can be in written or electronic form and you're allowed to keep your own evidence for expenses of less than $10 (providing the total of these expenses is not more than $200) and where you have been unable to obtain written evidence such as tolls or parking fees where you couldn't get a receipt. Some expenses are treated differently. If you're claiming car expenses, for example, you can choose between four methods of calculating the tax deduction.

Sounds simple enough. Where do people get it wrong? Common problems include not being able to substantiate your claims and claiming for expenses that are not work-related. This isn't always as simple as it seems. One mistake that regularly crops up is claims for self-education expenses.

These are only deductible if they relate to your current job not if you're studying on the side to get a better one. Travel to and from work is also not generally deductible.

Each year the Tax Office also examines returns to find occupations where the average claims are high, there are more people making claims, and a lot of people are making claims for the first time. This year its hit list includes truck drivers, sales and marketing managers, sales reps, and electricians.

Granger says common errors in these occupations include having insufficient documentation to support motor vehicle and travel expenses; claiming the living away from home allowance without proper documentation and verification from the employer that the employee must live away from home as a condition of their employment; motor vehicle expenses for carrying bulky equipment required for work without verification that their employer requires them to carry this equipment as part of their employment; and incorrect home office, mobile phone and internet expenses. The Tax Office has guides for these and other professions at ato.gov.au/occupations, or you can phone them on 13 28 61.