“You must contact HMRC [a website address ending contact/self-assessment] if you have taxable profits from the property you rent.
“… if a notice in respect of Year 1 is given after 31 st October in Year 2 a return (whether electronic or not) must be delivered during the period of three months beginning with the date of the notice.”
“We’re sending you this letter because you owe tax from your Pay As You Earn (PAYE) income or we’ve looked at your circumstances and need you to complete a Self Assessment tax return.
“filing date”, in relation to a return or other document, means the date by which it is required to be made or delivered to HMRC;
“penalty date”, in relation to a return or other document, means the date on which a penalty is first payable for failing to make or deliver it (that is to say, the day after the filing date).