You can join an MTD service during the year, but earlier records still matter. Give your new accountant the records from the tax-year start and proof of any updates already sent. Agree who will deal with outstanding updates, corrections and the annual return before the next deadline.
Find out what has already been sent
Make a short list of earlier update periods. Mark each as submitted, outstanding or uncertain, and name the person who handled it. Keep the software confirmations with the underlying records. Your recollection is helpful, but it is not the same as proof that HMRC received the update.
Give the new accountant the year so far
MTD updates are cumulative. If you join before the third update, the accountant needs the records from the tax-year start, not just the latest three months. Share exports, invoices, bank records and adjustments, including any previous corrections.
Agree the starting work and cost
Three situations need different plans: earlier updates are correct, they need correction, or they have not been sent. Ask which work your new package includes and get any catch-up charge agreed before it starts. A new subscription does not itself clear an overdue filing.
Send this with your enquiry: “I need support for 2026/27. My first two updates were filed by another accountant. I have the confirmations and records. Please confirm what you need before the next update and whether reviewing the earlier work costs extra.”
Keep the earlier annual return on the list
Your 2025/26 Self Assessment return and 2026/27 MTD work concern different years. Confirm who is finishing each one. Before buying MTD support, give TaxSimba the service year, income sources and submission history so the starting work can be agreed.
Make a handover sheet before choosing a start date
| Item | Record this |
|---|---|
| Business and reporting basis | For example: sole trade, standard periods, 2026/27. |
| Earlier work | Each period, its status and the confirmation held. |
| Next filing | The named firm responsible and its document cut-off. |
| Unresolved items | The missing record, who obtains it and the agreed review charge. |
Use one row per business. If the earlier submission status is uncertain, label it uncertain; do not guess that another firm filed it. Ask the incoming accountant to confirm acceptance of the records and next filing in writing.
Joining before the third update: a handover example
Illustrative example.
A sole trader joins a new service after two updates were sent by another accountant. The incoming accountant receives the earlier confirmations but no transaction export. Those confirmations show what was sent; they do not supply the underlying records needed to reconcile the next cumulative update.
The practical handover is therefore two-part: obtain the filing history and obtain records from the tax-year start. Agree who requests missing exports, checks the year-to-date totals and sends the next update. The example assumes standard update periods; confirm your actual accounting periods in the software.
| Check | Practical action |
|---|---|
| Earlier updates confirmed | Retain the business, period and submission evidence. |
| Earlier records missing | Request exports and supporting records before treating the handover as complete. |
| Correction identified | Agree who corrects the records and checks the next filing outcome. |
Can I start keeping records only from the joining date?
That leaves the incoming accountant without the earlier part of the tax-year picture. Arrange access to records from the start of the year.
Should I submit earlier updates again?
Check the existing filing history first. An unclear dashboard is a reason to investigate, not proof that every earlier update needs resending.
Download a checklist for this guide
- Joining date and next update deadline
- Businesses and accounting periods
- Previous submission confirmations
- Year-to-date records and exports
- Named owner of missing records and next filing