Tax Law, § 1139
Example 1:
A homeowner engages a contractor to erect a garage on a "furnish and install" contract. The agreed price of the garage completely erected is $2,400. The contractor purchases the building components without paying the sales tax due thereon. Upon completion of the garage, the contractor bills the customer $2,400 plus 7% tax or $2,568. The customer pays in full the amount billed and claims a refund of $168 for sales tax erroneously paid on a capital improvement. The refund is approved and paid. The contractor will be assessed the tax due on the building components purchased by him and any penalties and interest that have accrued.
Example 2:
A homeowner enters into a "cost plus" contract for the erection of a garage. The contract specifically provides that the home-owner will reimburse the contractor in full for all of the contractor's costs including sales tax paid by the contractor upon materials used. The contractor purchased $1,100 worth of materials upon which he paid $77, the proper rate of sales tax. The homeowner is given an itemized bill for materials and sales tax totaling $1,177 and pays it. The reimbursement of the $77 to the contractor for the tax paid is a contractual reimbursement by the customer of the contractor's expenses and not an erroneous collection of sales tax and may not be refunded or credited to the homeowner. The same would be true of any other charge itemized in the contract and bill for the capital improvement to real property.
Example 3:
A customer enters into a lump sum contract for a capital improvement. The contractor included the sales tax on his purchases of material in computing the contract price, and showed such sales tax separately in periodic billings to the customer. The customer later files for a refund of the sales tax. Such refund is not allowable since it was not a payment of tax by the customer; it was reimbursement of the contractor's expenses.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 534.8