New HMRC exclusions emerge in current online Self-Assessment filing: What to do about them

24th Jan 2018
Brought to you by
Share this content

BTCSoftware CEO, Rob Ellis, warns Agents of new and unanticipated HMRC exclusions impacting on current online Self-Assessment returns.

This January a number of new tax legislation and technical issues were always going to impact on the online Self-Assessment Filing – making it a more challenging season for Agents, Software Developers and HMRC.  The BTCSoftware team covered them in a post earlier in the month.

However, working closely with our customers and also HMRC’s Digital team, it has emerged that a number of new and unanticipated developments are impacting on current Self-Assessment Returns. I wanted to flag this to the Agent community as it may have a bearing on your clients’ returns.

New exclusions emerging

From our alerts to, and discussions with, HMRC’s Digital team 5 new exclusions relating to their systems have emerged and are affecting this year’s Online Self-Assessment Filing. We are waiting for further detail from HMRC.  Their Digital team have indicated they do not have time to adjust or issue a technical fix right now to software developers, nor would software developers be able to implement these before the deadline 31 January 2018. Just to emphasise these exclusions are in addition to the published list HMRC released in November.

What we are doing to help agents

We have been working closely with HMRC to alert them to these cases. In our 2018 Self-Assessment Software release (due in February) we will build a 2017 tax return checker which will go through all of the 2017 Individual Tax returns our clients have created and highlight the returns which HMRC need to recalculate.

What to do at this stage of the filing season

If you believe you have a return which is wrong, HMRC’s advice is to file online and then pay what is due or what you think is due. If you are paying less than the official calculation it would help your case to mention this in the additional information box on the main tax return form (SA100 box 19).

HMRC has said it will re-calculate the returns in error post January 31st. If the recalculation means, as a result of the official HMRC  computation being incorrect, you have paid too little tax then you will be expected to make up the shortfall but you should not be fined or be charged interest. Similarly if you have paid too much tax, you will get a refund.

It’s worth pointing out that HMRC believe the number of returns affected by these new exclusions will be very small compared to the total number submitted.

Self-assessment pre-population API

In our past post we also alerted agents to the technical issues HMRC was experiencing with its Pre-Population API. By way of a recap, the API was designed to enable agents to obtain and cross-check their clients’ figures in HMRC’s new Digital Tax Accounts when submitting a return in third party software.  The security measures HMRC put in place for the API included volume checks to prevent cyber-attacks flooding and bringing down the system.  In recent weeks the current volumes of returns calling on data via the API were causing it to issue an Internal Server/Protocol error.

Our close collaboration with HMRC meant we knew about the recent planned changes the SA pre-population API well in advance of their implementation.

Unlike other Self-Assessment software vendors we have not had to issue a very unwanted software update in January for these changes to take effect. We have also built in flexibility into our software so the API’s status doesn’t affect agent’s ability to submit a return. 

If you have the correct filing information and aren’t relying on the cross-check to the Digital Tax Account for the figures, you can complete and submit the return.  In BTCSoftware’s SA Solution, Agents can disable the API check if they wish – either for all their clients’ return submissions, or just for a specific one.  At BTCSoftware our friendly support team have been helping agents report the protocol error to HMRC and monitoring it closely.  Currently the previous pre-population technical issues appear to have been resolved.


In talking with both Agents and HMRC, this year’s online filing season has proved significantly more challenging.  With the sheer range of new taxation legislation to apply, along with HMRC’s ambition to further digitise tax filing, change (and learning from the changes) was inevitable. 

For some time, the BTCSoftware team has been planning, working-through and monitoring all these changes and their implications. Our core focus has been to deliver Self-Assessment software which is ‘fit and ready’ for the 2016/17 returns and help our customers navigate through the changes as effortlessly as possible. 

We will continue to work closely with our customers and alert, lobby and collaborate with the HMRC Digital team over any further unanticipated developments with the Gateway the minute they arise. We will continue to help and support accountants in their work for their clients.

Rob Ellis

CEO, BTCSoftware



Tel. 0345 241 5030