How the 18-Month Rule Works for Self-Employed Mortgages

Applying for a mortgage when you are self-employed can feel more complicated than it should. One of the most common questions we hear is: “How recent do my accounts or tax returns need to be?”

This is where the so-called 18-month rule comes into play. For some lenders, it can make the difference between moving ahead with your plans now or having to wait until the next set of accounts is available.

What is the 18-Month Rule?

Most lenders will ask for at least one full year of accounts or tax returns if you are self-employed. Traditionally, they prefer to see two or even three years of figures to assess affordability.

However, some lenders accept accounts or returns that are up to 18 months old at the time of application. This means that if your most recent tax year ended in April 2024, you could potentially apply for a mortgage any time up until October 2025 before being asked for the next year’s return.

Why Does It Matter?

Without this flexibility, many business owners and sole traders find themselves stuck waiting until their accountant finalises the next set of figures. This can delay house purchases or remortgages by months.

The 18-month rule allows certain applicants to move forward sooner, based on the most recent year’s income.

It’s also important to note that the 18 month rule could potentially work against you. For example, tax returns may need to be filed sooner than required if the latest available is older than 18 months old (i.e. if you are applying between October and April).

This could mean that your Accountant needs to file your return sooner than required and depending on their work load and your circumstances, this could cause delays. This is why preparation is key.

Who Can Benefit?

Newer businesses – If you only have one year of accounts, some lenders may still consider your application. Your track record, industry experience and credit profile will carry more weight.

Established businesses – If your latest return is still within 18 months, you may not need to rush into filing the next one before applying.

Professionals – Certain occupations (e.g. doctors, accountants, solicitors) may benefit from even more flexible underwriting

What Will Lenders Still Look At?

Even where the 18-month rule applies, lenders want reassurance that your income is sustainable. They may request:

• A letter from your accountant, sometimes including projections
  
• Evidence of previous employment in the same industry
  
• Company accounts, SA302s, and Tax Year Overviews
  
• Business and personal bank statements for consistency

Affordability checks also remain in place. Most lenders will allow around 4 to 5 times your income, although higher multiples may be possible for certain professional roles.

Points to Keep in Mind

• Not all lenders follow the 18-month rule — criteria vary widely.
  
• Specialist lenders may be more flexible, but this could mean higher rates or fees.
  
• Just because a lender can accept your accounts doesn’t mean they always will. A strong business case and professional advice are key.

Final Thoughts

If you are self-employed, understanding the 18-month rule could save you valuable time. It means you may not need to delay your plans simply because your next return is not yet ready.

That said, every lender treats self-employed income differently. Getting the right advice at the right time can make the difference between being told “come back next year” and getting the mortgage you need today.

Important Information

Your home may be repossessed if you do not keep up repayments on your mortgage.

There may be a fee for mortgage advice. The precise amount will depend upon your circumstances.

Symmonds de Lacey is a trading style of Easy Street Financial Services Ltd, which is authorised and regulated by the Financial Conduct Authority. Registered in England and Wales. Company number 6430453. Registered address: Basepoint, 377-399 London Road, Camberley, Surrey, GU15 3HL.

Please note, we are not tax advisers. For tax advice, please consult a qualified accountant or tax adviser.

Information correct at time of writing – September 2025