13 Feb CIS Contractors: How to Keep Job-by-job Records That Actually Work With MTD (Easy Guide for 2026)
If you're a CIS contractor, you've probably heard the whispers about Making Tax Digital for Income Tax Self Assessment (MTD for ITSA) coming in 2026. And yes, it means digital record-keeping is no longer optional: it's mandatory.
But here's the good news: job-by-job record-keeping doesn't have to be complicated or time-consuming. With the right system (and the right small business accountant in your corner), you can breeze through MTD compliance without the headache.
Let's walk through exactly what you need to do, how to set it up, and how software like Xero can make your life significantly easier.
Why Job-by-Job Records Matter for CIS Contractors
MTD requires digital records that track income and expenses separately for each project.
As a CIS contractor, you can't just lump all your jobs together and hope for the best. HMRC wants to see clear, accurate records for each project you work on. This means tracking what you earned, what you spent, and how you split costs between labour and materials.
Why does this matter? Because under the Construction Industry Scheme, the materials portion of your invoices isn't subject to the same CIS deductions as labour. If you can't separate these costs clearly, you could end up overpaying tax or facing questions from HMRC during an inspection.
Job-by-job records also help you:
- Understand which projects are actually profitable
- Spot patterns in your spending
- Make better decisions about pricing future work
- Prepare quarterly submissions without scrambling through shoeboxes of receipts
What Information You Need to Record Per Job
For each job, capture these essential details digitally:
- Date of every transaction
- Amount spent or earned
- Category (labour, materials, plant hire, subcontractor costs, fuel, etc.)
- Invoice details that clearly separate labour from materials
- Subcontractor information including their UTR and verification reference numbers if you're engaging other workers
The labour/materials split is absolutely critical. When you invoice a client for £5,000, you need to show how much of that was labour (subject to CIS deductions) and how much was materials (not subject to the same deductions).
Keep this information organized from day one. Don't wait until the end of the quarter to figure it out: you'll only make life harder for yourself.
Setting Up Your System: Practical Tips That Actually Work
On-site capture is your secret weapon.
The biggest mistake CIS contractors make? Leaving record-keeping until they're back at home, exhausted, and can't remember which receipt belongs to which job.
Here's what works better: use a mobile app or simply photograph receipts while you're still on site. Most modern accounting software has mobile apps that let you snap a photo, tag it to the right job, and categorize it instantly. This takes 30 seconds and saves hours of reconstruction work later.
Be specific with your labelling.
Instead of vague categories like "materials" or "expenses," get specific:
- "Materials – timber, Johnson renovation"
- "Labour – subcontractor Andy, kitchen fit"
- "Plant hire – scaffolding, Green Street extension"
This level of detail makes quarterly reporting straightforward and reduces the chance of errors. Your future self (and your CIS accountant) will thank you.
How Xero Makes This Easy for CIS Contractors
This is where being a Xero expert really helps our clients.
At Harrison's Accountancy, we specialize in Xero because it's genuinely brilliant for CIS contractors. Here's why:
Project tracking built-in: Xero lets you set up each job as a separate project. Every expense, invoice, and payment gets tagged to the right project automatically. At the end of the month or quarter, you can pull up a report showing exactly what you earned and spent on each job.
Mobile app for on-the-go recording: The Xero mobile app lets you photograph receipts, record mileage, and create invoices from your phone. Whether you're on a building site in Biggleswade or driving between jobs, you can keep your records up to date in real time.
Labour/materials separation: You can create invoice templates that automatically split labour and materials. This ensures your CIS deductions are calculated correctly every single time.
MTD-ready from day one: Xero is HMRC-recognized MTD software. When it's time to submit your quarterly updates, the software sends your figures directly to HMRC. No manual re-entering of data, no risk of transcription errors.
Bank feeds that save hours: Xero connects to your business bank account and pulls in transactions automatically. You just need to match them to the right job and category. This eliminates the need to manually enter every purchase.
We help our CIS clients get set up on Xero properly from the start, with templates, project structures, and workflows that match how you actually work. It's not about forcing you to change: it's about making the software fit your business.
Monthly Reviews: Stay Ahead of Quarterly Deadlines
Review your figures monthly, even though you only submit quarterly.
Here's a mistake many contractors make: they ignore their books for three months, then panic when the quarterly deadline approaches.
A better approach? Spend 30 minutes each month reviewing your records:
- Check that all receipts have been captured
- Ensure expenses are categorized correctly
- Verify that invoices show the labour/materials split
- Review subcontractor verification documents
- Confirm that CIS deductions match your expectations
This monthly habit keeps everything manageable. When the quarter ends, you're already 90% done: you just need to finalize the submission.
If you're working with a Xero accountant like us, we can handle these monthly reviews for you. We'll spot issues early, answer questions as they come up, and make sure you're always ready for the next quarterly deadline.
Tracking Subcontractors Properly
If you engage subcontractors, their records need special attention.
When you hire another contractor to work on your job, you need to record:
- Their full name and business details
- Their Unique Taxpayer Reference (UTR)
- Their CIS verification reference number
- Which job they worked on
- How much you paid them
- The CIS deduction you withheld
Xero's CIS module handles this beautifully. You can store subcontractor details once, then link them to specific jobs as needed. When you pay them, the software calculates the CIS deduction automatically and tracks what you owe to HMRC.
This is crucial for compliance. HMRC takes subcontractor verification seriously, and missing or incorrect information can trigger penalties.
Common Mistakes to Avoid
Don't fall into these traps:
Mixing personal and business expenses: Keep them separate from day one. Use a dedicated business bank account and credit card. This isn't just good practice: it makes your records cleaner and reduces questions from HMRC.
Forgetting mileage: If you're driving between jobs, that mileage is a legitimate business expense. Track it consistently using a mileage app or the notes function on your phone.
Not backing up digital records: Store everything in the cloud (Xero does this automatically) and ensure you have access to historical data. MTD doesn't eliminate your legal obligation to retain records for at least six years.
Waiting until year-end to sort things out: MTD is quarterly. Get into the rhythm of quarterly thinking. Your tax bill won't come as a surprise, and you'll have better cash flow visibility.
Trying to do it alone when you're overwhelmed: If record-keeping isn't your strength, don't force it. A good small business accountant who understands CIS can take this burden off your plate completely.
How We Support CIS Contractors at Harrison's Accountancy
We offer specialized CIS accounting support that takes the stress out of MTD compliance.
Here's what we do for our CIS clients:
- Set up Xero with project tracking and CIS modules configured properly
- Create invoice templates that automatically split labour and materials
- Handle monthly bookkeeping so you don't have to
- Verify subcontractors and track their details
- Submit quarterly MTD updates to HMRC on your behalf
- Provide year-round tax planning advice
- Explain your numbers in plain English (no jargon, no confusion)
We work with contractors across Bedfordshire and beyond, and we understand the unique challenges of working in construction. Whether you're a sole trader plasterer or running a small team of electricians, we can tailor our service to fit.
The digital transition doesn't have to be painful. With the right setup, it actually makes your life easier: you'll have better visibility of your finances, fewer surprises at tax time, and more time to focus on the work you're good at.
Ready to Get Your Records MTD-Ready?
MTD for ITSA is coming in 2026, but you don't need to wait until the last minute. Setting up proper job-by-job records now means you'll be ahead of the game, not scrambling when deadlines loom.
If you're feeling overwhelmed by the digital requirements, or you just want someone to handle it for you, get in touch with us. We'll walk you through exactly what you need, set up Xero to work for your business, and take the record-keeping burden off your hands.
MTD doesn't have to be stressful. With the right system and support, it's just another part of running a successful contracting business.
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