Do I have to pay CIS tax?

If you are a sub-contractor working within the construction industry, and assuming your work is subject to the regulations, then your contractor is obliged by law to pay you through the Construction Industry Scheme. If you haven’t applied for and been granted Gross Payment Status, then your contractor will deduct the standard rate of 20% from you, or if you are not known to HMRC the deduction rate is 30%.  The contractor is obliged to pay the deductions to HMRC, and issue you with a deduction statement.  If you are working for an end client or business that is not subject to the scheme your invoice can be paid gross.