Making Tax Digital for Income Tax doesn’t just change when you report — it changes how you record and submit. You can’t keep paper records and type a summary into HMRC’s website once a year. You need software that keeps digital records, sends quarterly updates to HMRC via API, and produces the end-of-year final declaration.
This is the hub for MTD software content on this site. Each section covers one piece of the software puzzle, with a link to the dedicated guide that goes deep. The sections that carry real weight are the ones no single spoke covers: the digital links rule, the software-vs-spreadsheet decision framework, how the HMRC API connection actually works, and the free-vs-paid trade-offs.
For the full MTD overview, see our Making Tax Digital guide. To check whether you’re in scope, see MTD qualifying income thresholds.
1. The digital links rule — what counts and what breaks it
The digital links rule is the single most misunderstood part of MTD, and it’s the reason a spreadsheet on its own isn’t enough. HMRC requires that your records flow from recording to submission through digital links — transfers of data between software components without manual re-entry. The rule exists to ensure there’s an unbroken digital audit trail from the original transaction to the figure submitted to HMRC.
What counts as a digital link:
- Formulas and cell references within a spreadsheet (e.g.
=SUM(Income!B2:B100)) - CSV or XML imports from one software component to another
- API feeds (bank feeds, accounting software APIs, platform exports)
- Automated email attachments that are imported by software
What breaks the link:
- Copy and paste between cells, sheets, or software — even once
- Retyping figures from one system into another
- Printing and re-entering data
The practical implication: if you use a spreadsheet for recording and bridging software for submission, the bridging software must read the spreadsheet directly (via file import or a live link). You can’t type the spreadsheet totals into the bridging software. For the full rules, worked examples, and HMRC’s specific guidance on each link type, see our can I use spreadsheets for MTD guide.
2. Software vs spreadsheet — the decision framework
This is the first choice every sole trader faces, and the answer depends on three factors: your transaction volume, your comfort with spreadsheets, and your budget.
Use full accounting software if:
- You have more than ~50 transactions per month — manual spreadsheet entry becomes a bottleneck
- You want bank feeds that import transactions automatically
- You want the software to calculate your tax estimate as you go
- You’re willing to pay £3-£25/month (or use a free tier)
Use a spreadsheet plus bridging software if:
- You have fewer than ~50 transactions per month
- You’re comfortable with spreadsheets and already use one
- You want the cheapest possible option (some bridging software is free)
- You don’t need bank feeds or real-time tax estimates
The break-even isn’t just about cost — it’s about time. A spreadsheet that takes you 2 hours per quarter to reconcile and update may cost less in software fees but more in your time than a £10/month accounting app that automates the same work. For the full comparison of spreadsheet bridging options, digital link requirements, and when each approach wins, see our can I use spreadsheets for MTD guide.
3. The cheapest MTD-compatible options
You don’t have to spend a lot. Several MTD-compatible options are free, and others cost less than a coffee per week. The cheapest routes are:
- Free tiers — some accounting software offers free plans for sole traders with low transaction counts (e.g. FreeAgent free with a Starling business account, Pie Tax free tier, Coconut Side Hustle at £3.60/month)
- Spreadsheet plus free or low-cost bridging software — if you already keep records in a spreadsheet, bridging software adds the HMRC submission layer for a few pounds per month
- Bank-integrated accounting — some business bank accounts include accounting software and MTD filing at no extra cost
The trade-off with free options is usually feature limits: transaction caps, no bank feeds, no invoicing, or no mobile receipt capture. For the full comparison table — including free options, paid plans, and which software includes what — see our cheapest MTD software for sole traders guide.
4. Cloud accounting — do you need it?
Cloud accounting software (FreeAgent, Xero, QuickBooks, Coconut, Pie Tax) handles everything in one place: bank feeds, expense categorisation, invoicing, quarterly updates, and the final declaration. It’s the most hands-off option, but it’s also the most involved to set up and the most expensive if you’re on a paid plan.
You probably need cloud accounting if you want bank feeds, automatic transaction categorisation, real-time tax estimates, or if you have an accountant who needs access to your books. You probably don’t if your records are simple, your transaction count is low, and you’re comfortable with a spreadsheet. For the full explanation of what cloud accounting is, how it differs from desktop software and spreadsheets, and whether it’s worth the cost for your situation, see our cloud accounting for sole traders guide.
5. How software connects to HMRC — the API authorisation process
This is the piece nobody explains, and it’s the source of most “my MTD software won’t submit” problems. MTD-compatible software doesn’t submit to HMRC through a web portal — it uses HMRC’s API gateway, a system that lets authorised software send data directly to HMRC’s servers.
The authorisation process works like this:
- You sign in to your software and choose to connect to HMRC.
- You’re redirected to HMRC and asked to log in with your Government Gateway credentials.
- You grant the software permission to submit MTD updates on your behalf.
- HMRC issues an access token to the software, which it uses for all future submissions.
- The token expires periodically and must be re-authorised — usually every 90 days, though some software handles this automatically.
The important thing to understand is that once authorised, your software submits quarterly updates without you logging into HMRC. You don’t see a “submit” button on HMRC’s website — the submission happens in the background through the API. If the token expires or the connection breaks, your updates will fail silently until you re-authorise. This is why checking your software’s HMRC connection status regularly matters — see section 7 below.
6. Is MTD software tax-deductible?
Yes — and this reduces the real cost by 20-40% depending on your tax band. Accounting software, bridging software, and the software element of a business bank account’s bundled accounting are all allowable business expenses under HMRC’s BIM35805 (software expenses) and BIM46450 (tax return preparation costs) guidance.
A £15/month software subscription costs £180/year. At basic rate (20%), the tax saving is £36 — so the real cost is £144. At higher rate (40%), the saving is £72 — real cost £108. This is true whether you use the cash basis or accruals basis. For the full rules, the BIM references, and worked examples at different price points, see our is MTD software an allowable expense guide.
7. When the HMRC link breaks
This is the most common MTD software problem, and it usually surfaces at the worst time — when a quarterly update deadline is approaching. The symptoms are typically: your software shows “connection failed” or “authorisation expired”, or a quarterly update submission returns an error.
The most common causes are:
- Expired access token — re-authorise through your software’s HMRC connection settings
- Changed Government Gateway credentials — if you’ve reset your password or changed your 2-step verification method, the old token is invalid
- Software migration — if you switch from one accounting software to another, the old software’s authorisation must be revoked and the new one authorised
- Bank-integrated software changes — if your bank changes its accounting tool (e.g. Starling’s migration from its old Business Toolkit), the old HMRC link stops working
The fix in almost every case is to re-authorise the connection through your software’s settings. For the specific case of Starling Accounting’s MTD link failing — one of the most common instances of this problem — see our Starling Accounting MTD link failed troubleshooting guide.
8. Free vs paid — what you get and what you lose
The free vs paid decision isn’t just about price — it’s about what features you sacrifice and how much manual work you take on. Here’s the practical trade-off:
| Feature | Free tier / spreadsheet | Paid software (£10-£25/month) |
|---|---|---|
| MTD quarterly updates | Yes (via bridging software) | Yes (built in) |
| Bank feeds | Usually no | Yes, automatic |
| Receipt capture (mobile app) | No | Yes, most paid plans |
| Real-time tax estimate | No | Yes |
| Invoicing | Manual or basic | Built in, branded |
| Multi-user / accountant access | No | Yes |
| Automatic categorisation | No | Yes, with rules |
| Support | Community/forum only | Email or phone support |
The pattern is clear: free options handle the minimum MTD requirement (digital records + quarterly submission), while paid options handle the surrounding workflow (bank feeds, receipt capture, categorisation, invoicing, tax estimates). If you’re spending more than an hour or two per month on manual bookkeeping tasks that paid software would automate, the subscription usually pays for itself in time saved — even before the tax deduction.
The sweet spot for many sole traders is a free business bank account with bundled accounting software (e.g. Starling with its built-in MTD tool, or Mettle with FreeAgent included). You get bank feeds and MTD filing at zero monthly cost, with the option to upgrade to a paid accounting app if you outgrow the free tier.
The Bottom Line
- You need compatible software — not just for submission, but for keeping digital records throughout the year.
- The digital links rule is non-negotiable. No copy-paste between software components — use formulas, imports, or API feeds.
- Spreadsheets work, but only with bridging software that reads the spreadsheet directly and submits to HMRC.
- Free options exist — free tiers, bank-bundled software, and low-cost bridging tools. The trade-off is features and manual work.
- The software is tax-deductible — 20-40% of the cost comes back through your tax return.
- The HMRC connection can break — usually an expired token or changed credentials. Re-authorise through your software’s settings.
- Paid software saves time, not just money — if you’re spending hours on manual bookkeeping, the subscription pays for itself.
For the complete MTD overview, see our Making Tax Digital guide. For the practical step-by-step on filing your first quarterly update, see how to file MTD. For the full checklist of what to prepare before you start, see our MTD readiness checklist. For the complete jargon buster, see our HMRC jargon buster.