This deadline is relevant to individuals who need to complete a self assessment tax return for 2017/18 and wish to file the return in a 'paper' form. Self assessment returns submitted after this date must be submitted electronically.
Please note that this deadline is not relevant if we are going to submit an online return for you or you are going to deal with the completion of an online return yourself. The deadline for submission of online returns is 31 January 2019.
If we are already dealing with this matter on your behalf you need take no action.