If sales tax has been collected out of State, use tax is only due if the tax was paid at a rate less than 7%, based on the difference.
For example:You purchased a computer for $1,550 plus $50 for shipping from a seller located outside of New Jersey and paid no sales tax. Your use tax liability to New Jersey on this item is $112 ($1,600 x.07 = $112). - On a trip to Maine you purchased an antique desk for $4,000 and paid Maine sales tax at the rate of 5%. The difference, $80 (2% of the purchase price), is due to New Jersey as use tax.
Individual taxpayers report and remit use tax by either completing and filing the Use Tax Return (Form ST-18) within 20 days after property is brought into New Jersey or by reporting any use tax due on Line 45 of their resident income tax return, Form NJ-1040.