Last year some six million people claimed work-related clothing and laundry expenses, totalling nearly $1.5 billion.

Assistant Commissioner Karen Foat said while many taxpayers can make these claims, it was unlikely half of all taxpayers were required to wear uniforms, protective clothing or occupation-specific clothing to earn their income.

"You must have spent the money you are claiming on buying or cleaning eligible clothes," she said.

"While you don't need receipts for claims up to $150, we can ask how you calculated your claim. We may even ask your employer if you have a required uniform.

"Last year a quarter of all clothing and laundry claims were exactly at the record-keeping limit. But don't think that we won't scrutinise a claim because we don't require receipts."

Also of concern to the ATO is the number of people claiming deductions for conventional clothing.

Some retail workers claimed normal clothes because their boss told them to wear a certain colour, or items from the latest fashion clothing line.

Others thought they could claim normal clothes because they only wore them to work.

"Your workplace may expect you to wear clothing items like suits or black pants," Ms Foat said.

"But an official 'dress code' doesn't qualify as a uniform and you can't make a claim for normal clothing, even if your employer requires you to wear it, or you only wear it to work."

The ATO's sophisticated data analytics were able to identify unusual claims by comparing taxpayer claims to others in similar occupations.

"Our data analytics will flag claims that are significantly above the average in occupations that regularly claim for laundry, like chefs or security guards," Ms Foat said.

"It will also flag claims made by people in occupations that usually don't claim, like office workers.

"We don't ignore incorrect claims just because they are small, because small amounts add up.

"No matter how small, it's not OK to expect other Australians to pay for your dodgy claims.

"The ATO will be taking strong action this tax time to protect honest taxpayers who are claiming the right amount - no more and no less."

Taxpayers who were unable to substantiate their claims should expect to have them refused, and may be penalised for failing to take reasonable care when submitting their tax return, Ms Foat said.

Are you claiming $150 or less for clothing and laundry (and less than $300 for work-related expenses in total)?

Make sure your claim is for eligible clothing (occupation-specific, protective or uniform). Remember, you cannot claim for plain or conventional clothing, even if your employer requires you to wear it and even if you only wear it to work. Calculate your claim for washing, drying and ironing at:

You may be asked to demonstrate how often you wore your eligible clothing (for example, evidence you worked three shifts a week for 48 weeks in a year)

A retail assistant working in a fashion store claimed more than $700 for store brand clothing she had purchased and was expected to wear to work. As the clothing was conventional she was not able to claim a deduction, and her claim was disallowed.

A stockbroker claimed the cost of purchasing suits which he regarded as his 'work uniform'. While many workplaces have a written or unwritten dress code, his suits were considered conventional or everyday clothing and his claim was refused.

Conventional clothing such as black trousers and a white shirt, or a suit, were not sufficiently distinctive or unique to your employer.

Clothing in a specific colour or brand was not enough to classify clothing as a uniform.