Self Assessment: Attachments to online return
General information
On 1 November 2006, an additional feature was added to allow you to submit online attachments with your online Self Assessment return.
In the majority of cases, it should not be necessary for you to attach accompanying material to your return. If you want to give us more information in support of your entries, you can enter this in the ‘Additional Information’ box.
There may be some situations, however, where we require you to send us additional supporting documentation with your online Self Assessment return, and in these circumstances, the online Self Assessment attachments feature can be used.
One example of where we would expect additional documentation is in the case of ‘Capital Gains’, where a claim for gifts hold-over relief is being made. In these circumstances, you would be required to attach a claim for this relief to your Self Assessment return.
If, after reading all the relevant Self Assessment return guidance, you are still unsure whether an attachment is appropriate, please ring either your tax office or, when the office is closed, the Self Assessment Helpline.
When use of the Self Assessment Attachment feature is not appropriate
The online Self Assessment attachments feature must not be used to submit
- A further Self Assessment Tax Return
- An amendment to any Return
- PDF (Portable Document Format) file versions of supplementary Pages, whether copied from our own forms or otherwise. This is because the attachment service is intended only for accompanying documents and will not process the data in this kind of attachment.
Some supplementary Pages can be submitted using HMRC software, with a greater range being commercially available.
Online submission of any supplementary Pages will only be acceptable if the submission is made using an approved software product designed specifically for that purpose.
Technical detail
To successfully use the online Self Assessment attachments feature, please note the following:
- The attachment will need to be a true PDF file which can be created by, for example, using software such as Adobe Acrobat Writer or by using a basic scanner.
- Total file size must not exceed 5mb. We would expect any attachment you submit to be well below this limit and instances where the upper limit is reached to be very rare. As a steer, we suggest you submit no more than the equivalent of 20 pages of plain text. Examples of what a 5mb PDF file might look like are; 500 pages of plain text - generated from Microsoft Word or Excel; or 150 pages scanned in black and white at a resolution of 150dpi; or 7 pages scanned in colour at a resolution of 300dpi). To minimise the size when creating a PDF file, we recommend that you do not use colour and ensure there are no logos or images within the document. If using a scanner, use a low scanning resolution, i.e. 150dpi.
- HM Revenue and Customs online Self Assessment product will not allow submission of more than 20 attachments with your online return and the total file size of these attachments must not exceed 5mb (see above).
- The online Self Assessment attachments feature will transmit PDF files quicker if using a broadband (or equivalent) connection. If you use a telephone dial-up facility (i.e. not broadband or equivalent), the speed with which PDFs will transmit may be very slow, and so, if possible, you should avoid peak periods, i.e. 10:00–16:00 weekdays and the week leading up to 31 Jan filing date.
- Any attachment must:
- be virus free
- not be encrypted
- not be password protected, i.e. we must be able to read and print it, and
- not have additional files embedded within it.
- The dollar ($), hash (#) and underscore (_) characters are not allowable in the title of any attachment file sent with a return.
Additional considerations:
- The online Self Assessment return and any accompanying attachments are received as a single online file
- If you do not follow the above guidelines, there is a risk that neither your online SA return nor any accompanying attachments will be accepted by HMRC and a possible penalty for failure to make a return on time will be charged.
What we do on receipt of the Self Assessment online return and attachment
We will not routinely review attachments and you should therefore only attach material supporting the return and not something that requires a direct reply.
But, we will examine attachments to ensure they do not contain information relevant to any enquiry that we may make prior to opening such an enquiry.
