CIS Subcontractor Bookkeeping: The Smarter Way to Stay on Top of Your Tax

If you work as a CIS subcontractor, your bookkeeping is not as simple as just adding up what landed in your bank account.

A contractor may deduct tax before paying you, materials may be treated differently from labour, receipts can easily disappear between jobs, and your final tax position depends on whether everything has been recorded correctly throughout the year.

That is why CIS bookkeeping needs a slightly different approach. It is not just about keeping records for HMRC. It is about knowing what you actually earned, what has already been deducted, what expenses you can claim, and how much tax you may still need to pay.

Under the Construction Industry Scheme, contractors deduct money from subcontractor payments and pass it to HMRC. These deductions count as advance payments towards the subcontractor’s tax and National Insurance.

For many subcontractors, the real problem is not the CIS scheme itself. The problem is keeping everything organised while working on site, moving between jobs, buying materials, receiving contractor statements and trying to avoid a stressful tax return at the end of the year.

That is where Kletta helps: Bookkeeping built for CIS subcontractors

Why CIS bookkeeping is different

Most sole traders only need to track income, expenses and receipts. CIS subcontractors usually need a more detailed view.

You may need to record:

• gross labour income
• cost of materials
• CIS tax deducted
• net amount paid into your bank
• expenses and receipts
• private jobs outside CIS
• rental income, if you also have property income

This matters because the amount you receive in your bank is not always the same as your true income. If a contractor has deducted CIS tax before paying you, that deduction still needs to be recorded properly so your tax position is accurate.

Registered CIS subcontractors normally have deductions taken at 20%, while unregistered subcontractors may face deductions at 30%.

If those deductions are not tracked clearly, you can easily lose sight of how much tax has already been paid on your behalf.

The common mistake: treating net payments as the full picture

A common mistake for subcontractors is to look only at the money that arrives in the bank.

For example, if you invoice for labour and materials, but the contractor deducts CIS from the labour element, the payment you receive is already reduced. If you only record the net payment, your bookkeeping may not show the full picture.

Good CIS bookkeeping should show:

This is the difference between simply storing numbers and actually understanding your business.

Why CIS subcontractors need to get ready for MTD

Making Tax Digital for Income Tax is changing how sole traders and landlords report income and expenses to HMRC. From 6 April 2026, sole traders and landlords with qualifying income over £50,000 must use compatible software to keep digital records, send quarterly updates and submit their tax return.

This is especially relevant for CIS subcontractors because bookkeeping can no longer be something you only deal with once a year.

Instead, your records need to be kept digitally and updated regularly.

That means the best time to improve your bookkeeping system is before the deadline creates pressure.

For CIS subcontractors, MTD is not just a compliance change. It is also an opportunity to stop relying on paper receipts, screenshots, WhatsApp messages, spreadsheets and last-minute accountant emails.

What good CIS bookkeeping software should do

A good bookkeeping system for CIS subcontractors should be practical enough to use while working, not only when sitting at a desk.

It should help you:

• upload receipts as you go
• store CIS contractor statements
• separate labour, materials and deductions
• track expenses clearly
• see your real profit
• prepare for MTD requirements
• handle CIS, private work and rental income in one place

Kletta is built around this kind of workflow.

Instead of leaving your bookkeeping until the end of the month or the end of the tax year, you can add receipts, track income and keep your records organised directly from your phone.

How Kletta helps CIS subcontractors

Kletta is designed for UK sole traders who want bookkeeping to feel simple, clear and manageable.

For CIS subcontractors, Kletta helps you keep everything in one place: CIS income, contractor deductions, expenses, receipts, private jobs and rental income if you have it.

Kletta supports CIS income from contractors, normal invoices for private customers, card payments, bank transfers, cash income, rental income and property-related expenses.

With Kletta, you can:

• track CIS deductions
• upload CIS statements
• add receipts from your phone
• organise labour, materials and expenses
• keep business and property records separated
• get a clearer view of your tax position
• get support from a real accountant when needed

The aim is simple: less admin, fewer surprises and a clearer picture of what is happening in your business.

Built for how subcontractors actually work

CIS subcontractors are rarely sitting at a laptop all day.

You might be moving between sites, buying materials, dealing with contractors, checking payments and trying to keep records while doing the actual work.

That is why mobile-first bookkeeping matters.

With Kletta, you can add receipts when you get them, upload contractor statements when they arrive and keep your records organised before they become a problem.

Instead of trying to remember everything later, you can handle the admin in seconds as you go.

CIS, private jobs and rental income in one app

Many subcontractors do not only work through CIS.

You might also do private jobs for homeowners, receive payments outside CIS, use card payment tools, or earn rental income from one or two properties.

Kletta is built to support this mixed income reality. On Kletta’s CIS page, the product is positioned specifically for subcontractors who need to track CIS work, private work and rental income clearly in one place.

This is important because your tax return depends on the whole picture, not just one income stream.

When everything is separated clearly, you can better understand your profit, deductions and upcoming tax position.

Why waiting until the tax deadline is risky

Leaving CIS bookkeeping until the last minute creates unnecessary stress.

By the time your tax return is due, you may need to find missing receipts, check old contractor statements, remember which jobs were CIS and which were private, separate materials from labour and work out whether all deductions have been recorded correctly.

That is avoidable.

A better system is to keep records updated throughout the year, especially now that MTD requires more regular digital record keeping for many sole traders and landlords. HMRC’s MTD guidance states that affected users need compatible software to create and store digital records, send quarterly updates and submit their tax return.

For CIS subcontractors, this means the future of bookkeeping is not a box of receipts at year-end.

It is a live, organised system that works throughout the year.

Final thought: CIS bookkeeping should make your business clearer

The best bookkeeping software does more than help you stay compliant.

It helps you understand your business.

For CIS subcontractors, that means knowing what you earned before deductions, what has already been paid to HMRC, what expenses you can claim and how much profit you are actually making.

Kletta brings that into one simple app, with support for CIS deductions, receipts, expenses, private work, rental income and MTD-ready digital records.

If you are a CIS subcontractor and want a simpler way to stay on top of your bookkeeping, Kletta is built for exactly that.

FAQ 

Do CIS subcontractors need to track gross income and deductions?

Yes. The net amount paid into your bank does not always show the full picture. You should track gross labour, materials, CIS deducted and net payment so your tax position is accurate.

Can I claim back CIS deductions?

CIS deductions count as advance payments towards tax and National Insurance for subcontractors. The way deductions are handled depends on your business structure and tax position, so your records need to be accurate.

Does Making Tax Digital affect CIS subcontractors?

It can. From 6 April 2026, sole traders and landlords with qualifying income over £50,000 must use compatible software for MTD for Income Tax. The rules apply to self-employment and property income.

Can Kletta handle CIS subcontractor bookkeeping?

Yes. Kletta is built to help CIS subcontractors track deductions, receipts, expenses, income, private work and rental income in one app.

Bookkeeping built for CIS subcontractors Track CIS deductions, receipts, expenses, private jobs and rental income in one mobile-first app.

Try Kletta today and make your bookkeeping easier from day one.