MTD for Income Tax: everything accounting firms need to know before April 2026

What is MTD for Income Tax?

Making Tax Digital for Income Tax Self Assessment — commonly referred to as MTD ITSA — is HMRC's programme requiring sole traders and landlords to move from annual Self Assessment tax returns to a system of quarterly digital submissions. It is the most significant change to UK income tax reporting in decades.

Under MTD ITSA, affected individuals must maintain digital records and submit quarterly updates of income and expenses to HMRC throughout the tax year, followed by an end-of-period statement and a final declaration. The annual Self Assessment return as most people know it is replaced by this continuous digital reporting process.

When does MTD ITSA start?

The rollout follows a phased income threshold approach:

Partnerships are not in scope for the initial rollout but are expected to be included in a later phase. Limited companies are subject to separate MTD for Corporation Tax legislation, which is still in development.

What does MTD ITSA require in practice?

Under MTD ITSA, each affected client must:

• Maintain digital records — all income and expenses must be recorded digitally, not on paper or in spreadsheets that aren't compliant software
• Submit quarterly updates to HMRC — four times per year, by the 5th of the month following each quarter end
• File an end-of-period statement (EOPS) — confirming the figures for the full year
• Submit a final declaration — replacing the traditional Self Assessment return, reconciling all income sources

The quarterly updates must be submitted using HMRC-recognised software with direct API connectivity — bridging software or manual data entry via HMRC's own portal is not a compliant route under MTD ITSA for most submissions.

What are the quarterly submission deadlines?

MTD ITSA quarterly periods align to the tax year, with submissions due within one month of the period end:

Clients can elect to use calendar quarter dates (31 March, 30 June, 30 September, 31 December) instead of the standard tax year quarters. This option is available to simplify bookkeeping for businesses that already work to calendar months.

What does this mean for accounting firms?

The impact on accounting practices is significant and often underestimated. The immediate production challenge is straightforward maths: if you currently manage 100 sole trader clients who file annual Self Assessments, MTD ITSA turns that into 400 quarterly bookkeeping submissions plus 100 end-of-period statements. That's a minimum 4x increase in production volume for the same client base — without adding a single new client.

For many practices, this is not something that can be absorbed by the existing team. Bookkeeping staff who currently handle annual work at a measured pace will be operating in continuous quarterly cycles from April 2026. The practices that build production capacity ahead of this date will thrive. Those that don't will be turning away clients or missing deadlines.

The client communication challenge

Most of your sole trader clients will not know MTD ITSA is coming. Many will assume their existing arrangement — sending you a bag of receipts once a year — will continue to work. It won't. Accounting firms who get ahead of this will need to proactively communicate what changes, what clients need to do differently, and what the new service looks like and costs.

Clients who currently pay for an annual Self Assessment return at a fixed fee will need to understand that MTD ITSA changes the service model entirely. The annual fee structure needs to be replaced with a monthly or quarterly service model. This is actually an opportunity for practices to increase recurring revenue — but it requires proactive client conversations well in advance of April 2026.

The software and infrastructure question

Under MTD ITSA, submissions must be made using HMRC-recognised software with direct API access. This means practices need to ensure their software stack is MTD ITSA compliant before April 2026. Xero, QuickBooks Online, FreeAgent, and a number of other platforms are or will be MTD ITSA compatible — but compatibility alone is not enough if your team doesn't have the capacity to process the work.

The more pressing question for accounting firms is not which software to use, but how to manage the production volume. Software stores data. Someone still has to do the bookkeeping that goes into it. For practices looking to scale without hiring, outsourced bookkeeping production — where a partner like bookd. handles the processing and delivers clean, review-ready output — is the infrastructure answer.

What are the penalties for non-compliance?

HMRC operates a points-based penalty system for MTD ITSA. Each missed quarterly submission earns a penalty point. Points accumulate over time and convert to financial penalties once a threshold is reached. The system is designed to be proportionate — occasional late submissions attract points but not immediate fines. Persistent non-compliance leads to financial penalties of £200 per missed submission once the threshold is breached.

Points can be removed by achieving a period of full compliance, but the reset period is twelve months. This means clients who fall into non-compliance can face accumulating points for an extended period before they clear the slate.

How should accounting firms prepare?

The firms that will handle MTD ITSA well are the ones preparing now, in 2025. There are three core actions that matter most:

1. Identify affected clients

Run a review of your sole trader and landlord clients. Identify who has income over £50,000 — they are in scope from April 2026. Flag those approaching £30,000 — they follow a year later. This gives you the client list to prioritise for onboarding, communication, and service restructuring.

2. Build or source production capacity

Work out the bookkeeping volume increase this will create for your team. If your firm processes 50 sole trader clients annually, you will need capacity to handle 200 quarterly bookkeeping cycles. Either that comes from hiring, from software automation, or from an outsourced production partner who can absorb the volume at a known per-client cost. Waiting until Q1 2026 to solve this problem is too late.

3. Restructure your pricing and service model

Annual Self Assessment fees do not work under MTD ITSA. The service is fundamentally different — it's continuous, it requires monthly or quarterly bookkeeping to be current, and it involves four times as many HMRC interactions per client. Most practices will need to move affected clients to a monthly recurring fee that reflects the new service model. The sooner this happens, the more predictable your revenue becomes going into 2026.

The bookd. answer to MTD ITSA capacity

bookd. is the white label bookkeeping engine for accounting firms. We process your clients' books — ingesting documents, classifying every transaction, reconciling ledgers, and preparing MTD ITSA quarterly submissions via direct HMRC API — and deliver clean, review-ready output to your practice within 48 hours.

For accounting firms facing the MTD ITSA volume increase, bookd. is the production infrastructure that absorbs the workload without adding headcount. Fixed per-client pricing means you know your cost before you quote. White label means your clients never know we exist. Direct HMRC API means no bridging software, no middleware cost, no submission failures.

If you're planning how to handle MTD ITSA for your practice, the best time to have that conversation is now.