I have been tutoring on a very casual basis - average £20 a week, although the plan long term is to do a lot more and I have new pupils wanting to start.
I read the gov.uk info and that suggests that my deadline, due to when I started, is October 2016:
_
Register as soon as you can after starting your business. At the latest, you should register by 5 October in your business’s second tax year.
Example
If you start working as a sole trader between April 2014 to March 2015, you should register before 5 October 2015. I started at the end of April 2015.
If you register later than this, you won’t get a penalty as long as you send your Self Assessment tax return and pay your bill on time.
_
But then on the penalty info it had this:
What is a failure to notify
There are certain circumstances that affect your liability to tax that you must tell us about, and you must
do so within certain time limits. If you do not do this, we call this a ‘failure to notify’.
The circumstances that you must tell us about include when you:
first become liable to pay tax
either carry out, or intend to carry out a taxable activity that must be registered with us
Examples of when you first become liable to pay tax include when:
your business exceeds the VAT registration threshold - you must tell us within 30 days of
this happening
the VAT supplies you make change - you must tell us within 30 days of this happening
your company first becomes chargeable to tax - you must tell us within 3 months of when the
company’s accounting period began
you are self-employed - you must tell us that you are due to pay Class 2 National Insurance contributions within 3 months from the end of the calendar month in which you started