Getting Started with Self Assessment for Businesses 

From April 2026, you’ll need to keep records of your business income and expenses in a digital format.

This guide will help you get an early start on MTD Income Tax Self Assessment (ITSA).

What is MTD ITSA?

MTD ITSA is a new way for self employed businesses and landlords to report earnings to HMRC. 

From April 2026, if your business and / or property has a gross total of £10,000 or more you’ll need to: 

  • Keep records of your business income and expenses in a digital format. 
  • Submit to HMRC using an MTD-Compatible software.
  • Send quarterly updates of the income and expenses of your business.
  • Finalise your business income and submit an end of period statement (EOPS) annually.  
  • Submit a final declaration of income annually.

We’ve been working on a Self Assessment area which will allow you to add your income and expenses to Dext Prepare and work alongside your accountant to submit this data directly to HMRC.

How can I access the Self Assessment area?

Once your accountant has created a Self Assessment account for your business, you’ll receive an email inviting you to Dext Prepare.

By accepting this invitation, you’ll be able to access the Self Assessment area. 

From here you’ll be able to edit or add details for your Income Source as well as submit and view transactions. 

What is a Transaction Collection Method?

A Transaction Collection Method is the type of documents you’ll be submitting to Dext Prepare and also sending to HMRC. 

You can choose either:

  • Receipts and invoices – Submit your invoices and receipts to Dext Prepare through the web app or mobile app.
  • Bank – Connect to a bank feed to have your transactions automatically added to Dext Prepare or submit your bank statements manually through the web app.

Note: You’ll either have the option to add receipts and invoices, or bank statements. You won’t see both options.

The Transaction Collection Method will have been selected by your accountant when setting up the Income Source in Dext.

We’d recommend reaching out to your accountant if you’d like to make any changes to this.

How to submit your documents into Dext

If your Transaction Collection Method has been selected as Receipts and invoices you can submit your documents by: 

  • Adding documents in the web app
  • Emailing your documents into Dext using your unique email in address
  • Setting up an invoice fetch connection
  • Using the mobile app

When logged into the web app, click the green Add Document button in the top left corner to access each of these submission methods. 

If Bank has been selected as the Transaction Collection Method, you can:

  • Set up a bank feed through the web app or the mobile app 

Add your bank statements using the green Add Documents button in the top left corner of the web app.

Categorising documents

You’ll need to add a category to each document submitted into Dext. There’s a set list of categories to choose from which have been set by HMRC. You can add a category in the web app by: 

For Receipts and invoices: 

  1. Navigating to your Cost or SalesInbox
  2. Select the relevent Category from the dropdown list for each item.

For Bank: 

  1. Navigating to Bank > Transactions.
  2. Select a Category from the dropdown list for each item.

Using the Mobile App

For Cost & Sales:

Use the green + button to capture images of your receipts and invoices.

Once you’ve captured your image, you’ll be able to add in additional information about the document as well as select a category.

For Bank:

If you can’t see the Bank section on the menu at the bottom of the screen, click More to access this area.

From here, you’ll be able to add and manage bank feeds, see transactions that have been added and add categories to these transactions.

For more information on this, take a look at this article.

Note: Bank statements will need to be submitted using the web app.

Switching between multiple Income Sources

If you have multiple Income Sources, you can use the account switcher drop down list to navigate between them. 

Key MTD Definitions 

Take a look at the below list for definitions of some of the key terms in MTD.

MTD ITSA Making Tax Digital for Income Tax Self Assessment.

Tax Individual – The Tax Individual is who the Self Assessment Tax Return will be submitted for.

Income Source – This represents the property or business for a given entity.

Transaction Collection Method – The type of documents you’ll be submitting to Dext, this willo either be receipts, invoices etc through Costs & Sales or bank transactions through bank statements or a bank feed. 

Quarterly Submissions – HMRC requires a quarterly submission of a businesses income and expenses.

EOPS – End of Period Statement. An EOPS will allow you to finalise your business income for a set period, this is usually when filing your annual tax returns.