Using Calendar Quarters for MTD ITSA (2026/27 Onwards)
From the 2026/27 tax year, HMRC allows eligible MTD ITSA users to submit quarterly updates using calendar quarters:
Q1. 6th April to 30th June (First Year Only)
Q2. 1st July to 30th September
Q3. 1st October to 31st December
Q4. 1st January to 31st March
This reporting option is available only to businesses with an accounting year running from 1st April to 31st March, which HMRC treats as equivalent to the standard tax year (6th April to 5th April).
Who Can Use Calendar Quarters?
Only businesses with a 1st April to 31st March accounting period may elect calendar quarters.
Important: HMRC guidance requires software providers to prevent the use of calendar quarters for any other accounting periods (e.g. 6 April to 5 April or 1 January to 31 December).
You must make this election in QuickFile’s MTD ITSA business details area before submitting your first quarterly update for the tax year. The selection applies for the full tax year and cannot be changed mid-year.
Quarterly Periods & Filing Deadlines (2026/27)
| Quarter | Period | Filing Deadline | Notes |
|---|---|---|---|
| Q1 | 6 April – 30 June | 5 August 2026 | Q1 6 April – 30 June 5 August 2026 Does not include 1–5 April — BSAS required for that period |
| Q2 | 1 July – 30 September | 5 November 2026 | |
| Q3 | 1 October – 31 December | 5 February 2027 | |
| Q4 | 1 January – 31 March | 5 May 2027 |
Reporting 1st–5th April via BSAS (First Year Only)
In the first year of MTD ITSA (2026/27), quarterly updates under the calendar quarter election begin on 1st April 2026. However, HMRC’s MTD obligations only commence from 6th April 2026.
This creates a 5-day reporting gap (1st–5th April) that must be accounted for separately using a Business Source Adjustable Summary (BSAS).
This step is only required in the first MTD tax year (2026/27). From 2027/28 onwards, no separate BSAS is needed, as the entire tax year will be covered by the quarterly updates (1st April – 31st March).
QuickFile will support this BSAS submission as part of the MTD self-assessment workflow.
Key Points Recap
- Calendar quarter filing is available only to businesses with a 1st April – 31st March accounting period.
- The election must be made before your first update is submitted.
- For 2026/27, Q1 runs from 1st April to 30th June, but as MTD obligations only begin from 6th April, you must separately report income and expenses for 1st–5th April 2026. HMRC requires this to be submitted through the Business Source Adjustable Summary (BSAS). From 2027/28 onwards, calendar quarters will fully cover the tax year (1st April – 31st March).
- Each update replaces the previous — there’s no need to resubmit prior quarters when corrections are made.