You must register for Self Assessment by 5 October if you’re a partner in a partnership.
You’ll need your partnership’s 10-digit Unique Taxpayer Reference (UTR). You can find a UTR if you’ve lost it.
You must also register your partnership if you’re the ‘nominated partner’.
There are different ways to register:
for limited liability partnerships
if you’re a partner that’s not an individual, for example a company or a trust