CIS Mortgages: How Much Can a CIS Subcontractor Borrow in 2026?

How Do Mortgage Lenders Assess CIS Income?

CIS mortgages can work differently from standard self-employed mortgage applications. If you work as a contractor or subcontractor under the Construction Industry Scheme (CIS), some mortgage lenders may assess your income using your recent gross CIS earnings rather than relying solely on the profit shown on your tax calculations or accounts.

This can make a significant difference to how much you may potentially be able to borrow.

If you are a first-time buyer, understanding how a lender will assess your CIS income before you start looking for a property can give you a much clearer idea of your potential budget.

The same applies if you are a home mover and need to understand how much you could potentially borrow for your next property.

As a mortgage adviser based in Romford, I regularly speak to people working in the construction industry who are earning good money but are unsure how a mortgage lender will assess their income.

The answer often depends on your working arrangement, how you are paid, your history under CIS, how long you have worked within the same type of employment and, in some cases, how long you have remaining on your current contract. Crucially, it also depends on which lender you approach.

Some lenders may treat you in a similar way to a standard self-employed applicant. This could mean assessing your income using documents such as:

SA302 tax calculations
Tax year overviews
Business accounts
Your declared taxable profit

Other lenders may have specific criteria for CIS contractors and subcontractors and may be prepared to assess your income using your recent gross CIS earnings, subject to their individual lending criteria.

For example, some lenders may use an average of your recent CIS earnings and calculate an annual income based on a 46-week working year. Depending on the lender, this could be evidenced using recent CIS payslips, payment statements or invoices together with matching bank statements.

The exact calculation and evidence required will depend on the lender. Some may use an average of your recent earnings, while others may assess your income differently depending on your working arrangement.

This can make a considerable difference.

An Example: Earning £250 Per Day Under CIS

Let’s take a CIS contractor earning £250 per day.

If they work five days per week for approximately 46 weeks of the year:

£250 × 5 days × 46 weeks = £57,500 gross annual income

A lender willing to assess the applicant using their gross CIS earnings may therefore potentially work from an income figure of around £57,500, subject to the lender’s individual calculation, lending criteria and evidence requirements.

In practice, a lender may calculate the income using an average of recent CIS earnings rather than simply relying on the stated daily rate. For example, some lenders may average the latest three consecutive months or 12 weeks of CIS income and then annualise that figure over a 46-week working year.

If we use a simple example of approximately 4.5 times income, an assessable income of £57,500 could indicate potential borrowing in the region of:

£57,500 × 4.5 = £258,750 maximum loan

This is only an illustration. Mortgage affordability is not based solely on a simple income multiple. Lenders will also consider your financial commitments, credit history, deposit, dependants, mortgage term and other expenditure.

However, it demonstrates why the way your income is assessed can be so important.

I help clients across Essex with a wide range of mortgage circumstances, and CIS income is a good example of why two lenders can look at the same person’s earnings very differently.

How Long Do You Need to Have Worked Under CIS?

There is no single minimum period that applies to every mortgage lender.

How long you have been working under CIS, how long you have worked within the same trade or type of employment and your current working arrangement can all be important.

Some lenders may want to see an established history of working under CIS or within the same type of work. Depending on the lender and the way you are employed or contracted, they may also consider how long you have been in your current role or contract and how much time remains on that contract.

For example, some contractor criteria may require a minimum period of continuous employment together with a certain amount of time remaining on the current contract. Other criteria may allow a lender to consider a longer history of continuous work in the same type of employment.

For CIS workers, some lenders have specific criteria that may allow them to assess recent consecutive months of CIS earnings, subject to the applicant meeting their individual requirements.

This means that someone who has recently changed the company they work for may not necessarily be treated in the same way as someone who has only recently started working in the construction industry altogether.

Your overall work history can therefore be just as important as the amount you currently earn.

What If You Are Assessed as Traditionally Self-Employed?

This is where the difference can become significant.

Let’s use the same CIS contractor earning £57,500 per year. If legitimate business expenses equivalent to 20% of their gross income reduce their taxable profit, this could result in a taxable profit of:

£57,500 minus 20% = £46,000 taxable profit

If a lender assessed affordability using the £46,000 taxable profit rather than the £57,500 gross CIS income, using the same simple example of 4.5 times income, the potential borrowing could be:

£46,000 × 4.5 = £207,000 maximum loan

Compared with:

£57,500 × 4.5 = £258,750 maximum loan

That is a potential difference of £51,750 in borrowing power.

This is only an illustration, as mortgage affordability depends on the lender’s individual calculation and your personal circumstances. However, it clearly demonstrates why the way a lender assesses your CIS income can make such a significant difference.

This does not mean that one method is right and another is wrong. It simply means that different lenders can assess the same applicant differently.

CIS mortgages are assessed differently by different lenders, which is why choosing the right lender can make a significant difference to your potential borrowing.

What Evidence Might a CIS Mortgage Lender Require?

The exact requirements vary between lenders, but you may be asked to provide some of the following:

Recent CIS payslips or payment statements
Recent invoices
Bank statements showing your CIS income
Evidence of your work history
Details of your current contract or working arrangement
Your latest tax calculations or SA302s
Tax year overviews
Evidence of your deposit
Identification and proof of address

Some lenders may ask for recent consecutive months of CIS income evidence together with matching bank statements. Others may assess you using your tax calculations, accounts or declared taxable profit.

Lenders may also have different requirements regarding how long you have worked under CIS, how long you have been working within your particular trade, your history of continuous employment and, depending on your working arrangement, how long you have remaining on your current contract.

There is no single set of rules that applies to every lender.

For CIS contractors living in Hornchurch, Chelmsford, Brentwood and Upminster, the key is finding a lender whose criteria fit your individual circumstances, rather than simply approaching the first lender you come across.