What is a co-ownership mortgage in Northern Ireland?

The short version

Co-Ownership is a not-for-profit housing association backed by the Department for Communities. It exists for people who can afford monthly payments but can't save a big enough deposit to buy a whole home. You pick a home on the open market, Co-Ownership checks it and checks you, and then the two of you buy it together.

You pay two things each month:

• Your mortgage, to a bank or building society, on the share you own.
• Rent, to Co-Ownership, on the share they own.

Over time you can buy more of the home until you own all of it. Around nine in ten co-owners end up doing exactly that.

A worked example

Say you find a house in Belfast for £180,000 and buy a 60% share.

• Your share is £108,000. That's what your mortgage covers (less any deposit you put in).
• Co-Ownership's share is 40%, or £72,000.
• Rent is 2.5% a year of their share: £1,800 a year, or £150 a month.
• For illustration, a £108,000 repayment mortgage over 30 years at 4.5% would be about £547 a month.

So the monthly cost is roughly £697, plus rates and buildings insurance. The mortgage rate you actually get will depend on the lender and your circumstances, which is where a broker comes in.

How the rent is worked out

The rent is 2.5% a year of the value of Co-Ownership's share, split into monthly payments by Direct Debit. If the home has a ground rent, that is added on. Service charges on apartments are paid separately.

The rent is reviewed every April and rises in line with inflation, and you get notice before it changes. Co-Ownership reports rent payments to Experian, so paying on time can help your credit file.

Because the rent is based on the part you don't own, it goes down every time you buy more.

Who can get one

For the standard Co-Own product you need to:

• be 18 or over and live in Northern Ireland with the right to reside here;
• not own any other property or land (some previous homeowners can still apply);
• be able to afford the purchase (Co-Ownership uses four times your pre-tax income as a guide);
• put any savings over £13,000 towards the purchase;
• have a clean recent credit history and bank statements, and at least six months in work (three years' accounts if self-employed).

Couples who are married, engaged or living together must apply together. There is also a separate Co-Own for Over 55s product, which lets you sell your current home and use the money towards a new one.

The home itself must be within the property value limit: £215,000 for existing homes and £230,000 for new builds (from 15 September 2026). Limits change from time to time, so check Co-Ownership's site for the current figure.

Buying the rest: staircasing

You can buy more of your home whenever you're ready, in steps of 5% or more, or all at once. This is called staircasing or buying out. Each step is priced at the home's value at the time, so a fresh valuation is needed.

Carrying on the example: five years later the house is worth £200,000 and you buy another 10%. That 10% costs £20,000, not £18,000, because the price has gone up. You now own 70%, Co-Ownership owns 30% (£60,000), and the rent drops to about £125 a month before any inflation increase.

Most people pay for staircasing by borrowing more, either from their current lender or by remortgaging to a new one. A broker can work out whether topping up, remortgaging or waiting makes more sense, and time it to avoid early repayment charges on your current deal.

Why the lender choice matters

Only some lenders offer co-ownership mortgages, and each has its own rules on deposits, income and how the rent counts in their affordability sums. Some will lend the full value of your share; others want 5% or 10% of it. A broker who does Co-Ownership cases regularly knows which lenders fit which situations, which saves time and avoids declined applications on your credit file.

For the scheme's wider rules and the points to weigh up, see our main Co-Ownership mortgages page.

Common questions

Figures checked 28 September 2026. The mortgage payment is an illustration only, not a quote.