CIS mortgages: how Construction Industry Scheme income is assessed

If you work in construction, you may have heard people talk about “CIS mortgages”. In practice, there isn’t usually a standalone mortgage product called a CIS mortgage. Instead, CIS is a way of showing your income to a lender when you’re paid through the Construction Industry Scheme (CIS).

This guide explains how CIS income is typically assessed, what lenders commonly look for when calculating affordability, and what to consider around deposits and credit history.

What is a CIS mortgage?

A CIS mortgage is shorthand for a mortgage application where your income is evidenced using CIS reporting rather than the usual self-employed profit figures.

Most lenders will still assess the application like any other mortgage—your income, outgoings, debts, deposit and credit history all matter. The difference is the type of income evidence you can provide.

How lenders assess CIS income

Under CIS, contractors can often evidence income using pre-tax figures shown on CIS statements. This can be helpful because many self-employed applicants are assessed using taxable profit (which may be lower once expenses and tax calculations are taken into account).

While each lender has its own process, common themes include:

• CIS statements are used to evidence how much you’ve been paid.
• Lenders may ask for recent evidence (for example, the latest months of CIS paperwork).
• Lenders may also consider how your work is structured—for instance, whether you’re consistently working through CIS and whether your income appears stable.

Because affordability is based on what you can realistically sustain, lenders will usually look for consistency rather than a one-off spike in income.

Who can apply using CIS income evidence?

CIS income evidence is generally available to people who are registered for CIS and paid under the scheme.

It’s not only for traditional site workers. Depending on how you’re engaged and registered, CIS may apply to a wider range of construction-related roles, such as:

• contractors and subcontractors
• tradespeople working under CIS arrangements
• some specialist professionals operating within the construction supply chain

If you’re not registered under CIS, you may need to rely on standard self-employed evidence such as tax year overviews and tax calculations.

Affordability: how much you could borrow

Mortgage affordability is usually assessed using two broad steps:

1. Income — the lender establishes a headline income figure.
2. Outgoings and commitments — the lender considers regular spending, existing debts, and any maintenance commitments.

With CIS income evidence, the headline figure may be based on the pre-tax CIS income shown in your statements, which can make a meaningful difference compared with profit-based calculations.

In the market, you may hear figures such as up to around 4.5 times annual income. However, the actual amount available depends on the lender’s rules, your circumstances, and the overall affordability assessment.

What evidence is usually required?

Exact requirements vary, but CIS mortgage applications commonly involve providing:

• CIS statements covering the relevant period
• identification and standard mortgage application documentation
• details of your employment/contracting arrangements
• information about existing debts and monthly commitments

Some lenders may also ask for additional supporting documents if there are gaps in income, changes in your contracting status, or other factors that affect stability.

Deposits for CIS mortgages

Deposits work in broadly the same way as for other borrower types.

• A larger deposit often improves the options available.
• Many lenders tend to offer their most competitive pricing around 10% or more.
• It may still be possible to buy with a smaller deposit depending on lender criteria and the property.

If you’re considering a smaller deposit, it’s especially important to understand how affordability and credit history interact with the lender’s risk appetite.

Getting a CIS mortgage with bad credit

Having adverse credit doesn’t automatically rule you out, but it can affect which lenders are willing to consider your application.

Key points to bear in mind:

• Many mainstream lenders prefer borrowers with a strong credit profile.
• If your credit history is weaker, you may need to consider specialist options.
• Adverse credit can lead to less favourable pricing and/or more cautious underwriting.

CIS income evidence can still be valuable in these cases because it may help demonstrate income clearly. However, lenders will still weigh the overall risk based on your credit file, the stability of your income, and your ability to meet repayments.

Common misconceptions about CIS mortgages

A few misunderstandings come up frequently:

• “CIS mortgages are a separate product.” In most cases, they’re not—your CIS income is simply evidenced differently.
• “CIS income always means you can borrow more.” It can help, but affordability depends on outgoings, debts, and how consistent your income is.
• “If I have CIS statements, I don’t need anything else.” Lenders still require standard mortgage documentation and will assess your overall financial position.

Summary

CIS mortgages are best understood as mortgages where your income is evidenced using Construction Industry Scheme reporting, often allowing lenders to consider pre-tax income rather than profit figures.

If you’re a CIS-registered contractor, the main factors that typically influence your application are:

• the evidence and consistency of your CIS income
• your overall affordability (including debts and commitments)
• the deposit you can put down
• your credit history and how it affects lender choice

If you’d like, you can also explore related home-buyer guides on deposits and mortgage affordability to build a clearer picture of how the pieces fit together.