CIS Mortgages: Specialist Mortgage Advice for Construction Industry Scheme Workers

What Is a CIS Mortgage and Why Does It Matter?

The Construction Industry Scheme (CIS) is a tax framework used across the UK building and construction industry. Under CIS, contractors deduct tax at source from payments made to subcontractors before passing the remainder on. This means CIS workers receive income net of tax deductions, rather than as gross pay or as trading income after expenses.

This creates a specific and well-known problem when applying for a mortgage. Many standard lenders look at bank statements and see only the net income after CIS deductions, leading them to significantly underestimate a subcontractor's true earning capacity. In practice, a CIS worker earning well above the average UK wage can find themselves offered a mortgage based on a figure that bears little resemblance to what they actually earn.

The solution is not to accept that position as fixed, but to work with an adviser who understands how CIS income works and knows which lenders are willing and able to assess it properly. At J Finance, we have helped CIS workers across the construction industry secure mortgages that reflect their real earnings, and we know exactly how to approach these applications.

How Do Lenders Assess CIS Income?

This is the most important question for any CIS worker applying for a mortgage, and the answer varies considerably between lenders.

The net income problem

Standard lenders who use bank statements as their primary income evidence will typically see only the net amounts received after CIS tax deductions. For a subcontractor subject to the standard CIS deduction rate of 20%, this means the lender is effectively assessing income based on 80% of gross earnings. For those on the higher 30% deduction rate, the gap is even larger.

Using gross CIS earnings

A growing number of lenders now specifically accommodate CIS workers by using gross earnings before CIS deductions as the basis for income assessment, rather than net receipts. To do this, they typically require CIS statements from the contractor showing gross amounts, CIS deductions, and net payments across a period of at least six to twelve months, often twelve months to cover seasonal variation.

This is the approach that produces the most accurate and favourable assessment for most CIS workers, and identifying lenders who take this approach is one of the most valuable things a specialist adviser can do.

Using self-assessment tax returns

Some lenders will use the income figure shown on the CIS worker's self-assessment tax return as their measure of income. This can be helpful where returns are up to date and show consistently strong earnings, but it requires accounts or tax returns to be current and accurately filed. Where returns show net profit after expenses, this figure may be lower than gross CIS earnings, which affects the outcome.

How much history is required

Most lenders want to see a minimum of twelve months of CIS trading history. Some will accept six months in specific circumstances. A longer track record of consistent earnings generally supports a stronger application. If you have been working in construction under CIS for several years, this history works in your favour.

Who Do We Help?

We advise CIS workers across the full range of construction trades and roles, including:

  • Bricklayers, plasterers, and general builders working as subcontractors under CIS

  • Electricians and plumbers registered under CIS for construction site work

  • Carpenters, joiners, roofers, scaffolders, and specialist tradespeople

  • Civil engineering and groundworks contractors

  • Painting and decorating subcontractors

  • Labourers and general site workers paid through CIS

  • Sole traders working in construction who are registered for CIS deductions

  • CIS workers who also have some employed or self-employed income alongside their CIS earnings

  • Limited company directors in construction where the company operates under CIS

Common Challenges for CIS Mortgage Applicants

Seasonal or variable income

Construction work is naturally more seasonal in some trades than others, and income may vary significantly between summer and winter months. Lenders who assess monthly receipts without accounting for seasonal patterns can draw misleading conclusions about earning consistency. We work with lenders who take an annualised view of income and are comfortable with the natural variation in construction work.

Gaps between contracts

Brief gaps between contracts are normal in the construction industry and do not necessarily indicate financial instability. However, some lenders will treat gaps negatively if they occur during the assessment period. We advise on how to present work patterns clearly and identify lenders who understand the nature of contract-based construction employment.

Mixed CIS and employed income

Some construction workers combine CIS subcontracting work with periods of direct employment or vice versa. Presenting both income streams clearly and ensuring each is evidenced correctly requires careful handling to avoid confusion in the lender's assessment.

CIS workers operating through a limited company

Where a construction business operates through a limited company that is registered under CIS, the income assessment becomes similar to that of a company director, with salary and dividends needing to be presented correctly alongside CIS statements. We advise on the most effective way to structure this type of application.

Recently registered under CIS

If you have recently moved from direct employment into CIS subcontracting, your trading history under CIS may be shorter than lenders typically require. We advise on timing and approach, and identify lenders who are more flexible on minimum history requirements in the right circumstances.

What Documents Will I Need?

The specific documentation depends on your working arrangement and which lender we are targeting, but typically includes:

CIS payment and deduction statements from your contractor or contractors, covering at least the last twelve months. These show gross payments, CIS deductions, and net amounts received, and are the most important document for lenders using gross earnings assessment.

Business bank statements for the last three to six months, showing income deposits and business expenditure. For lenders looking at net receipts, this is their primary income evidence.

Personal bank statements for the last three months, showing living costs, existing financial commitments, and the management of personal finances.

Self-assessment tax returns and SA302 tax calculations for the last one to two years, where these are required by the lender.

Evidence of upcoming contracts or forward bookings where available, as this can help demonstrate ongoing income continuity.

Standard identity and address documentation required by all lenders.

We guide you through exactly what is needed for your specific application and help you prepare it correctly and completely.

How the CIS Mortgage Process Works

Step 1: Understanding your income and circumstances

We start with a thorough conversation about how you work, your CIS registration, your income history, and what you are looking to achieve. This shapes which lender is right for you and how your application should be structured.

Step 2: Lender selection

We identify the lenders whose criteria are most favourable to CIS income, and specifically those who are prepared to assess gross CIS earnings rather than net receipts. This is often the single most impactful decision in the process.

Step 3: Documentation preparation

We advise you on what documents are required and help you gather and present them effectively. CIS statements in particular need to be clear and complete, and we ensure the income narrative presented to the lender is as strong and accurate as possible.

Step 4: Application submission and management

We prepare and submit your application, handle lender queries, and keep you updated throughout underwriting.

Step 5: Offer and completion

Once your mortgage offer is issued, we help you understand the terms and any conditions attached, and support you through to completion.

Tips for CIS Workers Applying for a Mortgage

Keep your CIS statements. Your contractor is required to provide monthly CIS payment and deduction statements showing gross amounts and deductions. Keep these organised and accessible, as they are the most important document for CIS mortgage applications. If you are missing any, contact your contractor to request replacements.

Ensure your self-assessment tax returns are up to date and accurately reflect your CIS income. Some lenders rely on tax returns as their primary income evidence, and being behind on returns can delay or prevent an application entirely.

Maintain a clear business bank account. Having CIS income paid into a dedicated business account separate from personal spending makes it much easier to demonstrate income patterns to lenders.

Do not approach multiple lenders simultaneously. Each application leaves a credit footprint, and multiple searches in a short period can indicate financial difficulty to subsequent lenders. Working with an adviser who identifies the right lender before submitting an application avoids unnecessary searches.

Build your CIS trading history where possible before applying. While there are lenders who will consider shorter histories, having twelve months or more of consistent CIS earnings considerably widens the range of products and lenders available to you.

Be prepared to evidence future work where possible. A letter of intent from a contractor or confirmation of upcoming projects can strengthen an application by demonstrating income continuity beyond the historical period.

Get Started with J Finance

We work with CIS contractors and construction industry subcontractors across the UK, helping them present their income correctly and access mortgage products that reflect their true earning capacity. Appointments are available by phone, video, or face-to-face at our Newbury office, with out-of-hours slots available on request.

To arrange a no-obligation conversation, call us on 01635 521300 or email contact@jfinance.co.uk.