You can download forms and guidance to help you send your tax return either online or by post. 

You must send your tax return by the deadline (external link) or you will get a penalty (external link)

The Main Tax Return (SA100) 

There are two ways to do a Self Assessment tax return. You can: 

• file your Self Assessment tax return online (external link) 
• download and fill in form SA100 (external link) 

Getting Help 

You can: 

• get advice from a professional, such as an accountant (external link) 
• contact HM Revenue and Customs (HMRC) (external link) 
• use the notes and helpsheets (external link) 

Only fill in the short tax return (SA200) if HMRC sends it to you. You can not download it, but you can read the guidance notes (external link). 

Extra Sections 

You might need to fill in more sections, known as ‘supplementary pages’, if you are telling HMRC about these types of income: 

• employees or company directors - SA102 (external link) 
• self-employment - SA103S (external link) or SA103F (external link) 
• business partnerships - SA104S (external link) or SA104F (external link) 
• UK property income - SA105 (external link) 
• foreign income or gains - SA106 (external link) 
• capital gains - SA108 (external link) 
• non-UK residents or dual residents - SA109 (external link) 

Check the full list of supplementary pages (external link) to make sure you fill in the right sections if you are sending your return by post. 

If you are sending a tax return for the 2014 to 2015 tax year or earlier, get forms from the National Archives (external link)

Sending a Tax Return if you are not an Individual  

There are special forms if you are sending a tax return for a business partnership or non-resident company, or if you are a trustee.