Inland Revenue is sending the construction sector a final warning to get on top of business tax obligations.

40,000 businesses with outstanding debt and overdue returns will be sent emails and letters in the coming months.

Inland Revenue spokesperson Richard Philp says the current outstanding tax debt sits just shy of a billion dollars.

"We'll be writing to most - some we'll try to prompt with a text message, but most of them we'll be writing to. It won't be the first contact we've had with them."

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