Most dentists stay with the wrong accountant because they think moving is a hassle, or awkward, or has to wait for year-end. None of that is true. Here is exactly how switching works, how long each step really takes, and how far back a new accountant can put things right.
Guide · Updated August 2026
There is no rule that you have to wait for your year-end or the end of the tax year. You can move accountants whenever you like, including mid-year, and a competent new firm will pick things up cleanly from wherever they are. The only thing worth reading first is your current engagement letter, for any notice period and for how work in progress is charged on exit.
Making Tax Digital added one timing consideration for anyone inside the regime. Quarterly updates are due on 7 August, 7 November, 7 February and 7 May, and your new agent has to be authorised with HMRC before the deadline they are expected to file. Since authorisation takes a fortnight or so, a switch started in late October is tighter than the same switch started in August. It is a reason to start early, not a reason to wait — our Making Tax Digital guide sets out the deadlines in full.
Once you appoint a new accountant, they write to your old one. The letter is a professional clearance request, and it does two jobs: it asks whether there is any professional reason not to act, and it requests the information needed to take over. This is a routine exchange between two firms governed by their professional bodies' ethical codes, not a negotiation and not a confrontation.
Nothing about the switch is slow except the post, and knowing which step is the binding constraint lets you plan around it.
An associate's practice has been deducting superannuation on an estimated pensionable pay figure of £48,000, which sits in the 9.8% tier — £4,704 a year. Her actual pensionable pay has been £61,000 for three years, which sits in the 10.7% tier and should have produced £6,527 a year.
The under-deduction is £1,823 a year. Across three years that is £5,469, and it is recovered in a lump when NHSBSA reconciles the estimate against the actual. Nothing was hidden and nobody did anything wrong; the estimate simply never got updated, and no one whose job it was to look at the pay statements was looking for it. That is the single most common thing a dental-specialist accountant finds in the first month. Our NHS pension guide works the tiers, the annualisation trap and the annual allowance in pounds.
Expenses are the other side of it. Business mileage between two practices — 1,656 qualifying miles at the 55p rate that applied from 6 April 2026 — is a claim of £910.80. Never claimed, that costs a higher-rate associate £382.54 a year in tax, and an associate whose profits fall in the £100,000 to £125,140 band, where the personal allowance taper pushes the marginal rate to 62%, £564.70 a year. Our expenses guide lists what is genuinely allowable.
Switching is not only forward-looking. Two separate windows let a new firm correct the past.
So an associate switching in August 2026 who has never claimed their inter-practice mileage can recover it for 2022/23 onwards, not just going forward. That is four years of a £382.54 annual saving — over £1,500 — from a single corrected claim. It is also a window that closes on a fixed date, which is the practical argument for switching now rather than at the year-end.
Any accountant can file a tax return. A dental accountant knows the things that quietly cost dentists money: superannuation deducted on stale estimates, the annualisation rule that charges a part-year associate as though they earned a full year, associate self-employment and the agreements behind it, the expenses that are legitimately claimable in dentistry, and the tax around buying and selling a practice. If you are switching, switch to someone who does this all day — otherwise you have moved for nothing. See who we help: associates, practice owners and hygienists and therapists, and our associate tax guide shows the level of detail to expect.
Two situations are worth pausing for. If you are mid-enquiry with HMRC, moving firms is possible but adds a handover into a process that is already running to someone else's timetable — usually better to move once it closes. And if your accounts are within weeks of a filing deadline, moving first and filing second risks both; agree with the incoming firm which of the two happens first, in writing, before you give notice.
Beyond that, switching is quick, you do not handle the awkward part, and it can happen whenever suits you. The only real question is whether your current accountant genuinely understands dentistry. Have a no-pressure chat and we will tell you what we would look at first.
Deadlines coming up, rule changes that affect dentists, and one number worth checking — once a month, no spam.
No, and most of it is handled for you. You appoint the new firm, they send a professional clearance letter to your outgoing accountant and manage the handover of records and HMRC authorisation. The only thing you personally do is tell your current accountant you are moving, and pass on the authorisation code HMRC posts to you. That code letter arrives within 7 working days and has to be used within 30 days of its date, so opening the post promptly is genuinely the main thing asked of you. Door to door, a straightforward switch takes about two weeks.
Yes. There is no need to wait for your year-end or the end of the tax year, and a competent new firm picks things up from wherever they are. Check your current engagement letter for a notice period and for how work in progress is charged on exit. If you are inside Making Tax Digital, the one timing point is that your new agent must be authorised before the quarterly deadline they are expected to file — 7 August, 7 November, 7 February or 7 May. Since authorisation takes roughly a fortnight, that is an argument for starting early rather than delaying.
No. Agent authorisation is simply re-registered to the new firm and your tax references do not change. Your UTR stays the same, your company's details stay the same, and there is no gap in your affairs being handled provided the authorisation is completed before the next filing deadline. The one situation worth pausing on is an open HMRC enquiry: moving firms mid-enquiry is permitted, but it inserts a handover into a process already running to someone else's timetable, and it is usually cleaner to complete the enquiry first and move immediately afterwards.
Often, and there are two separate windows. A filed return can be amended for 12 months after its filing deadline, so a 2024/25 return due on 31 January 2026 can be amended until 31 January 2027. For earlier years, an overpayment relief claim can be made up to four years after the end of the tax year, so 2022/23 remains open until 5 April 2027. An associate who has never claimed inter-practice mileage worth £382.54 a year in tax can therefore recover four years of it, not just claim it going forward. Both windows close on fixed dates.
Because dentistry has specifics a generalist routinely misses. NHS superannuation is deducted on estimated pensionable pay, and a stale estimate at the 9.8% tier against actual pay in the 10.7% tier under-deducts £1,823 a year — recovered in a lump when NHSBSA reconciles. Add the annualisation rule that charges a part-year associate as though they earned a full year, dental-specific expense rules, associate self-employment, and the tax around buying or selling a practice. None of that is exotic to a firm that does it daily, and all of it is easy to miss for a firm that sees one dentist a year.
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