Changing Lanes Mid-Journey: Moving Your MTD Records to New Software Without Losing Count

Choosing your first piece of bookkeeping software often feels like a small decision. It is only later — when transaction volumes grow, a second income stream appears, or the quarterly MTD for Income Tax submissions begin in earnest — that the limitations show themselves. If you have reached that point, you are not alone. A growing number of sole traders and landlords are now planning a software move, and the most common worry we hear at Pomfrey Accountants is a simple one: will I lose count of where I am?

The reassuring answer is that a properly planned migration loses nothing. A careless one, however, can double-count income, misstate your opening balances and turn your first quarterly update into a reconciliation exercise. This guide sets out how to make the move cleanly.

Why People Outgrow Their First Choice

Most people settle on their first software because it was cheap, free, or recommended by a colleague. That is a perfectly reasonable way to start. The friction usually appears later, for one of three reasons.

First, scope. A tool that handled a simple self-employed trade may struggle once you add rental accounts, a partner's income, or multiple income streams that MTD requires you to report separately.

Second, bank connectivity. Older or budget tools sometimes have unreliable bank feeds. When transactions stop importing automatically, manual entry errors creep in quietly.

Third, MTD readiness. Not every product on the market is listed by HMRC as compatible for Making Tax Digital for Income Tax. If yours is not, the switch is not optional — it is a deadline-driven necessity.

Before You Touch Anything: Pick Your Cut-Off Date

The single most important decision in any migration is the date you stop recording in the old system. The cleanest approach is to switch at a natural boundary — the start of a new tax year (6 April), a quarter, or at least the start of a month.

A mid-week, mid-transaction switch is how double-counting happens. If an invoice exists in both systems and both feed into your records, your turnover is overstated and your tax position is wrong. Choose a cut-off, reconcile the old system up to that date, and enter nothing after it in the old tool.

Export Everything — and Check the Exports

Before cancelling anything, export the complete history from your current software. At minimum you will want:

• A full transaction listing (income and expenses) covering the whole of the current tax year to date
• Your trial balance or category totals as at the cut-off date
• Customer, supplier and property records where relevant
• Copies of outstanding invoices and bills
• Bank reconciliation reports showing what has and has not been matched

Download these as spreadsheets and, ideally, PDF copies of key reports. Keep them somewhere permanent. Software companies can close, merge or change their export formats, and your records remain your responsibility regardless.

Setting Opening Balances in the New System

This is the step where migrations go wrong. Your new software starts from zero, so it needs to be told where you stand as at the cut-off date.

The core figures to enter are:

• Bank balances for every business account, exactly as they stood at the cut-off
• Money owed to you — outstanding customer invoices, entered individually
• Money you owe — unpaid supplier bills and any credit card balances
• Category totals for anything else that carries forward, such as a prepayment or a running balance on a loan

A useful sanity check: the sum of your opening balances should reconcile to your bank statements plus any receivables and payables. If it does not, stop and find the discrepancy before recording a single new transaction. Fixing an opening balance error three months later is far harder than fixing it on day one.

Avoiding the Double-Counting Trap

Double-counting has two usual causes. The first is re-entering transactions that straddle the cut-off — an invoice issued in March but paid in April, recorded in both systems. The rule is straightforward: record income and expenses once, in the period they belong to, in whichever system owns that period.

The second cause is re-importing bank feeds. If your old software's feed runs on past the cut-off date, those transactions can find their way into both tools. Cancel the old feed immediately, and when you connect the new one, set its start date to the cut-off so history is not pulled in twice.

Run the Two Systems in Parallel — Briefly

For the first month or so, it is worth leaving the old system dormant but intact rather than deleting it. Reconcile your first month in the new software against your bank statement and, if anything looks odd, you have the old records to compare against. Once one clean quarter has passed and your first MTD update has been accepted without issue, you can archive the old account with confidence.

A Note on Timing and Deadlines

If your migration is being driven by an MTD for Income Tax deadline, build in margin. Signing up, learning a new tool and reconciling opening balances all take longer than expected — particularly if the switch lands near a Self Assessment deadline in January. Starting the move well before the quarter in which you must first submit removes most of the pressure.

How We Can Help

Software migrations are far more routine than they feel from the inside. At Pomfrey Accountants we regularly review opening balances, check cut-off reconciliations and confirm that a client's chosen tool is HMRC-compatible before the first submission is due. If you are contemplating a switch, a short conversation before you begin is invariably cheaper than untangling a problem afterwards. Get in touch and we will help you change lanes without losing count.