Making Tax Digital for locksmiths: what changes from April 2026

TL;DR: Making Tax Digital for Income Tax Self Assessment (MTD ITSA) applies to self-employed UK locksmiths in three income steps: over £50,000 from 6 April 2026, over £30,000 from 6 April 2027, and over £20,000 from 6 April 2028. Three real changes land at once: digital records must be created by each relevant update deadline (HMRC recommends creating them as close to the transaction date as possible), you submit four quarterly updates from compatible software each year on top of your Self Assessment tax return using compatible software, and you need compatible software. The underlying tax calculation does not change. Same money, different rhythm. Locksmiths face specific wrinkles around emergency call-out income that arrives irregularly and often in cash, stock carried in the van, mileage that accumulates invisibly, and the revenue split between 24-hour emergency jobs and scheduled installation or maintenance work. Quarterly reporting makes all of these more visible than a once-a-year tax return ever did. This post sets out what actually changes, what stays the same, and how to stay compliant without over-engineering your record-keeping.

Current HMRC rule: Each update is calculated by compatible software from digital records and covers cumulative category totals from the start of the tax year to the end of the update period - not only the previous three months. If record keeping and filing use different software, keep a permitted digital link between them; manual re-keying or clipboard transfer is not a digital link. HMRC will not apply penalty points for late quarterly updates in 2026/27, but the updates must still be sent before you submit your Self Assessment tax return using compatible software. Check HMRC digital-record guidance, quarterly-update guidance and HMRC's current MTD journey.

2026/27 simplified mileage rate: For self-employed simplified expenses, HMRC's rate for cars and goods vehicles is 55p per business mile for the first 10,000 miles and 25p per business mile after that. The 55p rate applies retrospectively from 6 April 2026. Check GOV.UK simplified vehicle expenses before relying on the figures.

If you work as a self-employed locksmith or sole-trader security specialist in the UK, the MTD ITSA headline is straightforward. Mandatory digital records and quarterly updates in three steps:

• From 6 April 2026, qualifying income over £50,000.
• From 6 April 2027, qualifying income over £30,000.
• From 6 April 2028, qualifying income over £20,000.

Qualifying income is your combined self-employment and property income. If you operate a van from a home base and also rent out storage or equipment alongside your locksmith work, that rental income counts toward the same total.

The three real changes:

1. Digital records from the start, not reconstructed at year-end. Your income and expense records must be created by the relevant update deadline and kept in a structured digital format; HMRC recommends creating them as close to the transaction date as possible. A spreadsheet can work if it pairs with compatible software connected through a permitted digital link. Some cloud accounting software can handle both record keeping and filing; check HMRC's current compatible-software list and the provider's supported features. Pulling a folder of receipts and cash job notes out of the van in January is no longer a compliant approach.
2. Four quarterly updates per tax year, plus a Self Assessment tax return using compatible software. Each update contains cumulative totals for the categories you use, from the start of the tax year to the update-period end. The tax calculation still happens at year-end. The rhythm changes, not the complexity.
3. Compatible software. The existing self-assessment portal will not accept MTD ITSA submissions. You need cloud accounting software with direct MTD submission built in, or a spreadsheet paired with compatible bridging software that supports the workbook and a permitted digital link.

Worth saying plainly: quarterly figures are provisional. They are not mini tax returns. They show HMRC your business is active and give a running picture. No additional tax calculation happens at the quarterly stage.

Most service businesses have relatively clean income and expense categories. Locksmith work has layers that matter specifically for quarterly reporting.

Emergency call-out income: irregular, often cash, time-of-day variable. A locksmith taking calls at midnight receives cash on a different rhythm from a business issuing invoices and receiving bank transfers two weeks later. Under MTD, every payment received must be recorded digitally in the period it arrives. Cash jobs that were previously noted loosely and reconciled at year-end now need to be entered at the time. This is not a new tax obligation. Cash income has always been taxable. It is a new recording discipline that catches up with anyone who has been informal about it.

24-hour versus scheduled job revenue split. Emergency lockout work and planned installation or maintenance work have different revenue rhythms. Emergency call-outs often arrive unpredictably across all seven days. Scheduled work (door installations, master-key suites, access control upgrades) is invoiced and collected on a more predictable pattern. Both are taxable income in the period received, but the two streams can create a cumulative income figure at the update-period end that looks uneven if emergency volume spikes or drops. That unevenness is normal and expected under MTD. The quarterly figures do not need to be balanced.

Stock tied up in the van. A working locksmith carries cylinders, padlocks, key blanks, mortice locks, euro-profile locks, barrel bolts, and a range of door furniture at any given time. Some of that stock will be used on jobs in the current quarter; some will carry forward. For quarterly reporting, the question is when to record the stock cost. HMRC's approach for sole traders is generally that materials and consumables are recorded as a business expense when purchased, not when used on a specific job. If you buy a batch of cylinders at the start of a quarter and use half of them by the end, the full purchase cost is still recorded in that quarter as an expense. Your Q1 expense figure may therefore look higher than your Q1 income in a quarter when you have stocked up. This is normal. Quarterly figures are not required to be balanced.

Mileage tracking. A mobile locksmith covering a service area puts on significant mileage. Emergency call-outs to residential addresses, commercial premises, and vehicle lockouts all accumulate. If you use HMRC's self-employed simplified-expenses mileage rate (55p per mile for the first 10,000 miles, 25p thereafter), you record mileage rather than actual vehicle costs. The discipline under MTD is keeping a mileage log throughout the quarter, not reconstructing it at year-end. The time required varies with transaction volume, record quality and the software you use; the continuing duty is to keep accurate digital records and check the software-generated update.

Cash income discipline. The locksmith trade has a higher-than-average proportion of cash payment on emergency residential jobs. Under quarterly reporting, every cash receipt needs to be in your records in the quarter it arrives. A simple same-day log (date, job address, amount received, cash or card) is sufficient. The discipline is the point.

A quarterly update reports income and expenses by category. The categories you will typically track on the expense side for a sole-trader locksmith:

• Consumables and stock: cylinders, lock bodies, key blanks, padlocks, door furniture, barrel bolts, access control hardware.
• Tools and equipment: lock picks, plug followers, key-cutting machines, decoders, programming devices. Items replaced regularly and below the capital threshold.
• Vehicle costs: van insurance, fuel, servicing, road tax. If you use the flat mileage rate, you record mileage totals rather than actual vehicle costs.
• Insurance: public liability, tools and equipment cover, employer's liability if you engage staff.
• Training and qualifications: Master Locksmiths Association (MLA) membership fees, DBS check costs, any locksmith training courses or trade body renewal fees.
• Advertising and marketing: Google Ads, directory listings, website hosting, any printed marketing.
• Professional fees: accountancy fees, any legal or compliance costs.
• Phone and communications: the business proportion of your mobile and any call-out answering service costs.
• Software: accounting software subscriptions, call management tools, invoicing applications.
• Bank charges: business account fees, card processing costs for in-person card payments.

Your software sends cumulative totals for each category at every update, not individual receipts. The receipts and records stay with you.

Your software uses either standard update periods or calendar update periods. Each update is cumulative, not a separate three-month return. Under standard periods the coverage runs 6 April-5 July, 6 April-5 October, 6 April-5 January and 6 April-5 April; under calendar periods it runs 1 April-30 June, 1 April-30 September, 1 April-31 December and 1 April-31 March. The corresponding deadlines are 7 August, 7 November, 7 February and 7 May. The tax return is due by 31 January after the tax year.

The time required varies with transaction volume, record quality and the software you use; the continuing duty is to keep accurate digital records and check the software-generated update. The ongoing work is in keeping your income and expense records current throughout the quarter, not in the submission act itself. A locksmith taking two or three emergency call-outs a day has income arriving in small, frequent, sometimes cash amounts. The discipline is daily or weekly recording, not quarterly.

Cloud accounting software. Platforms such as Xero, QuickBooks, or FreeAgent at £12–£30 per month. They handle income recording, expense categorisation, mileage tracking, and cumulative MTD updates natively. Best fit: locksmiths with higher turnover, access control or commercial security contracts billed monthly, or those who also have staff and want one system handling payroll, invoicing, and tax records together.

Spreadsheet plus bridging software. You maintain your own spreadsheet recording income and expenses by category; compatible bridging software receives the records through a permitted digital link and submits the cumulative update to HMRC. Best fit: locksmiths with simpler finances, sole-trader operations with clear categories, and those already comfortable maintaining their own records in a structured way.

Hand it to your accountant. Your accountant manages the quarterly updates from the records you supply. The incremental cost for quarterly updates may be reasonable if they already handle your year-end. The catch: your accountant can only submit what you have recorded. You still need to maintain digital records between meetings. Handing a shoebox of receipts over in January will not work on a quarterly schedule.

There is no single right answer. The right tool depends on your transaction volume, your cash-to-card payment ratio, and how much of this you want to own yourself.

If your records are currently informal (cash jobs noted loosely, van receipts gathered approximately, mileage calculated from memory), the April 2026 deadline is the hard reset.

1. Separate business and personal money completely. A dedicated business bank account and card make every quarterly step faster and eliminate the most common source of errors.
2. Start a mileage log now. Every job you drive to: date, start and end postcode, miles. A simple notes app on your phone is enough if it is consistent.
3. Choose your approach. Cloud accounting, spreadsheet plus bridging, or accountant-managed. Set it up before the first quarterly period begins.
4. Record all cash income as it arrives. Every cash payment is income in the period received. A simple same-day log is sufficient.

If you do nothing else before April: open a dedicated business account and log every payment the same day it arrives. Everything else cascades from that.

Quarterly updates are still required. HMRC says it will not apply penalty points for late quarterly updates in 2026/27; for later tax years, missed update deadlines can generate penalty points and a financial penalty once the threshold is reached.

For the document side of running a locksmith business, including client services contracts, customer ID-verification procedures, photo records of works, and invoice templates, see essential business documents for UK locksmiths.

Check current GOV.UK guidance and HMRC compatible-software information for your own MTD obligations.

The kit pairs with the locksmith business documents bundle (£19.99) if you also want client contracts, customer access-verification logs, photo record templates, and the operational paperwork that sits alongside tidy quarterly accounts.

This article is general guidance, not tax advice. For your specific tax position, cash income treatment, and expense categorisation, consult a qualified accountant or tax adviser with sole-trader experience.