Changing accountants is not just a relationship decision. It is a compliance event with operational consequences. A clean switch keeps your MTD-for-ITSA quarterly cycle intact, your HMRC continuity obligations in order, your record-retention duty satisfied, and any in-flight obligations (open enquiry, 60-day residential CGT disposal, pending SDLT submission, LtdCo confirmation statement, LLP designated-member ID verification) running without a gap.

This page is the operational checklist for a landlord-side switch. Every step carries its operative legal or regulatory underpinning: TMA 1970 s.12B for record retention, SI 2026/336 (which on 1 April 2026 revoked SI 2021/1076) for Agent Services Account linkage, ICAEW PCRT and parallel professional standards for clearance, MLR 2017 reg 27 for AML, ECCTA 2023 Part 3 for the ACSP cascade where you operate a LtdCo or LLP. The page is not a sales pitch. It is the sequence to run, in order, with the operative anchor at each step.

Pre-Switch Tax-Side Checks

Before you notify the outgoing accountant or sign with a new firm, run these checks. A switch executed in the middle of an open obligation creates risk you do not want.

  • MTD-for-ITSA quarterly cycle state. Are you in-quarter or between quarters? The digital ASA handover sequence is materially cleaner if executed between submission windows. Mid-quarter switches require both firms to coordinate the inherited digital records, the reconciliation, and the next submission deadline.
  • Any open HMRC enquiry under TMA 1970 s.9A. You cannot switch agents mid-enquiry without an affirmative continuity protocol. The outgoing accountant must not abandon mid-enquiry; the incoming accountant must formally pick up. HMRC's compliance officer should be notified.
  • Any in-flight 60-day residential CGT disposal. TCGA 1992 Sch 2 paras 6 to 12 imposes a 60-day in-year reporting and payment window on UK residential disposals. If a disposal is mid-window, the window does not pause for agent change; either the outgoing accountant completes the submission first, or the new accountant onboards fast enough to hit the deadline (rarely feasible).
  • Any pending SDLT obligation. FA 2003 Sch 10 imposes SDLT return obligations within 14 days of completion on relevant transactions; ensure no SDLT return is pending submission at the moment of the agent handover.
  • Any IHT account-and-payment obligation. IHTA 1984 ss.216 and 226. Where you are an executor or personal representative with an in-flight IHT account, the obligation continues regardless of agent change.
  • For LtdCo and LLP landlords, any in-flight ECCTA-side ID verification. ECCTA 2023 Part 1 and Part 3. If the outgoing accountant is the ACSP and is mid-verification on a designated member or officer change, complete that step before switching the ACSP.

None of these checks is optional. They are pre-switch surprises rather than post-switch surprises if you map them before signing with the new firm.

Professional Clearance Protocol

The professional clearance protocol is operationally consistent across the major UK professional bodies: ICAEW Professional Conduct in Relation to Taxation (PCRT), the ACCA Rulebook, ATT and CIOT PCRT. The incoming accountant writes a clearance request to the outgoing accountant covering five standard areas:

  1. Any professional reason against accepting the engagement.
  2. Outstanding client matters.
  3. Unpaid fees position.
  4. Any AML concerns.
  5. Any HMRC enquiry or dispute state.

Critical operative point on unpaid fees. The PCRT framework distinguishes "reason to delay" (a real concern the new engagement needs to consider) from "reason to refuse" (a professional bar to engaging). An unpaid fee alone is NOT a professional reason to refuse engagement. The outgoing accountant can (and should) raise the unpaid fee with the landlord for contractual settlement, but cannot withhold clearance solely on that basis. This is one of the most common landlord misunderstandings: the outgoing firm has contractual rights over unpaid fees, but not a professional veto over the engagement.

The 64-8 and ASA Sequence

The HMRC agent authorisation mechanics have two distinct layers and you need both.

Layer 1: 64-8 / Online Agent Authorisation. The legacy 64-8 form (and its modern digital equivalent via HMRC Online Services) authorises the new agent for general HMRC correspondence and SA / CT / PAYE matters. The new accountant submits the authorisation; HMRC links the agent within typically 3 to 5 working days. The outgoing accountant's authorisation may be removed automatically by HMRC on confirmation of the new linkage, or may require an affirmative cancellation request; the current operative behaviour at agent change is evolving and should be verified.

Layer 2: Agent Services Account (ASA). The ASA is the digital framework for MTD-for-ITSA clients under SI 2026/336 (which on 1 April 2026 revoked the prior SI 2021/1076). ASA linkage is SEPARATE from the 64-8 authorisation. The new accountant requests ASA linkage for the landlord's MTD-for-ITSA registration. HMRC confirms ASA linkage typically 5 to 10 working days. Without ASA linkage in place, the new accountant cannot submit MTD-for-ITSA quarterly updates on the landlord's behalf.

Practical discipline. Retain copies of the 64-8 confirmation, the ASA linkage confirmation, and date-stamped acknowledgements. HMRC system gaps have caused dual-agent and zero-agent situations during agent changes; if uncertainty arises about the agent of record, contact HMRC directly to confirm before any submission.

Records Transfer: What You Receive and What the Firm Retains

On the landlord's instruction, the outgoing accountant transfers to the landlord (or to the new accountant directly):

  • The landlord's own documents (originals or copies).
  • Tax returns and computations prepared on the landlord's behalf.
  • HMRC correspondence.
  • Workings and supporting schedules where they are part of the landlord's record.

The outgoing accountant may retain (and is not obliged to release):

  • Internal working notes.
  • Firm-side standing audit or engagement files.
  • Opinions provided to other clients.
  • The MLR 2017 CDD file (the firm's own duty record).

Fall-back if the outgoing accountant is uncooperative: UK GDPR subject-access-request (SAR). The landlord is the data subject; the landlord can request own data direct from the firm under DPA 2018 and UK GDPR. The SAR is free and the firm has 1 month to respond. The SAR overrides any contractual lever the firm is using to delay records release.

The MTD-for-ITSA Quarterly Handover

For an in-scope landlord (qualifying income above the current mandate threshold: £50,000+ from April 2026; £30,000+ from April 2027; £20,000+ from April 2028 per Spring Statement 2025 confirmation), the quarterly cycle must continue uninterrupted across an accountant change.

Operational sequence:

  1. Sign engagement letter with new firm.
  2. New accountant submits 64-8 digital authorisation to HMRC.
  3. New accountant requests ASA linkage for the MTD-for-ITSA registration.
  4. HMRC confirms 64-8 (3-5 working days) and ASA linkage (5-10 working days).
  5. New accountant verifies inherited quarterly submission history (download from HMRC Online Services or MTD-compliant software) and reconciles against the landlord's records.
  6. Next quarterly submission made by new accountant as agent of record.

Timing recommendation. Switch BETWEEN quarterly windows. Complete the current quarter's submission with the outgoing firm; switch in the days following submission acknowledgement; the new firm onboards into a clean closed quarter and prepares for the next quarter. Mid-window switches work but require both firms to coordinate; if either firm misses the submission deadline, the landlord (not the firm) is responsible under FA 2009 Sch 55.

LtdCo and LLP: The ECCTA ACSP Cascade

For landlords with LtdCo or LLP structures, the agent change at the corporate-filings layer is distinct from the agent change at the personal-tax layer. Under ECCTA 2023 Part 3, the Authorised Corporate Service Provider (ACSP) framework imposes ID verification obligations on agents acting for companies and LLPs.

At agent change:

  • The outgoing ACSP's role is cancelled.
  • The new ACSP must register with Companies House.
  • The new ACSP conducts fresh ID verification on designated members (LLP) or officers (LtdCo). The outgoing ACSP's ID verification does NOT transfer.
  • Companies House confirms the ACSP change.

Timing risk. The ACSP transition can take 2-4 weeks depending on Companies House queue. Any Companies House filing during the gap (confirmation statement, accounts, PSC update) must be made through the ACSP of record. If the outgoing ACSP is cancelled before the new ACSP is registered, the filing window can be missed. Verify the next Companies House filing deadline and either complete it through the outgoing ACSP before cancellation, or have the new ACSP registered first.

Crucially, the personal-tax agent change is independent. You can change personal-tax accountant without changing corporate-filings ACSP, or vice versa. The two layers operate separately.

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AML Reverification at the New Firm

MLR 2017 SI 2017/692 reg 27 requires fresh customer due diligence (CDD) at engagement. The outgoing accountant's CDD file is the outgoing firm's own duty record; it does not transfer. The new firm conducts fresh CDD covering:

  • Identification (photographic ID).
  • Address verification.
  • Source-of-funds and source-of-wealth where relevant.
  • Politically-exposed-person (PEP) and sanctions screening.
  • Risk-rating against the firm's risk-based approach.

This applies at every agent change. There is no concept of "AML carry-over" between firms. Expect the new firm to request a portfolio overview, source-of-deposit evidence (especially for higher-value portfolios), and bank statement extracts where required by the firm's risk-based assessment.

Retention Obligation: Independent of Accountant

The landlord's record-retention duty is INDEPENDENT of the accountant. The accountant is a service provider holding copies; the landlord is the record-holder for primary obligations.

  • TMA 1970 s.12B. Individual self-assessment records: 5 years from 31 January following the tax year for non-business; for business records (including landlord business), 5 years 10 months.
  • CA 2006 s.388. Company accounting records: 6 years for private companies; 3 years for unaudited small companies (verify current statutory text).
  • TMA 1970 s.12AA. Partnership SA800 records: parallel to individual retention.
  • TCGA 1992 Sch 2 paras 6 to 12. 60-day residential CGT records: retain alongside SA records.

Where the accountant has retained working copies and the landlord has not retained originals, the landlord remains liable for the duty. The accountant's copy is not a substitute. Keep originals; the accountant holds copies.

Cost and Fee Mechanics

The transition cost stack:

  • New firm engagement fee. One-off setup plus ongoing fee structure. Property-business-focused firms often charge by portfolio scale; generalist firms by complexity.
  • Outgoing firm handover or closure fee. May be charged per the outgoing firm's engagement letter; review the contract for the fee structure on cessation.
  • Outstanding fees with the outgoing firm. Remain payable; professional clearance does not require them to be paid first, but contractual payment terms apply.
  • ACSP transition cost (LtdCo / LLP only). The new ACSP's fresh ID verification step typically carries a setup cost.
  • Data migration cost. Where the outgoing firm's MTD-compliant software differs from the new firm's, a one-off migration may be required.

For a typical 4-5 property BTL portfolio, expect a one-off transition cost of £500 to £1,500 plus ongoing fee differentials. For LtdCo plus LLP structures with ACSP cascade, add £200 to £500 for ECCTA ID verification. These are indicative; the actual cost depends on portfolio size, complexity, and the specific firms involved.

The Right Time to Switch

Timing recommendations against the operational calendar:

  • Cleanest break: immediately after a tax-year-end submission completion. The new accountant inherits a closed year and prepares for the next.
  • Before the new tax year's quarterly cycle starts. Avoids mid-cycle handover; the new firm onboards into a clean starting position.
  • For LtdCo landlords: around the accounting reference period end where possible. Clean financial-year break.
  • Avoid: mid-enquiry; mid-60-day-CGT window; in the run-up to a submission deadline; mid-ECCTA ACSP cascade.

Timing is a load-bearing variable. The same switch executed at a bad time creates operational chaos a well-timed switch avoids. If the outgoing firm relationship has degraded sharply and waiting for a clean window is not feasible, the alternative is to coordinate both firms with explicit handover documentation through the switch window.

For the record-retention framework under TMA 1970 s.12B, see the record-retention cluster pages. For the MTD-for-ITSA mandate timetable and the ASA mechanics, see the MTD cluster. For ECCTA 2023 and the ACSP framework, see the LtdCo and LLP cluster pages. For the 60-day residential CGT reporting under TCGA 1992 Sch 2 paras 6 to 12, see the CGT cluster. For the HMRC enquiry framework under TMA s.9A and s.28A, see the enquiry and discovery cluster. The integration across these compliance layers (the clean-switch sequence) sits on this page.