Barbara's liability to income tax and Class 4 NICs for 2016-17 was £26,000, of which £4,000 was deducted at source. Her liability for 2017 -18 is £30,000, of which £1,000 has been paid by deduction at source. State the dates on which Bar bara is required to pay her 2017-18 liability and compute the amount payable on each date.
Ignore Class 2 NICs and capital gains tax.