This deadline is relevant to small employers and contractors only. As a small employer with income tax, national insurance and student loan deductions of less than £1,500 a month you are required to make payment to HMRC of the income tax, national insurance and student loan deductions on a quarterly basis.
Where the payment is made electronically the deadline for receipt of cleared payment is Friday 20th July 2018 unless you are able to arrange a 'Faster Payment' to clear on or by Sunday 22nd July. In year interest will be charged if payment is made late. Penalties also apply.