Co-Own or a standard mortgage?

Co-Ownership is a Northern Ireland scheme that lets you buy part of a home and rent the rest. Through Co-Own you buy a share of a home between 50% and 90% and Co-Ownership buys the remaining share. You pay a mortgage on your share and rent on theirs¹. It is aimed at people who cannot afford to buy a home outright².

The practical difference from a standard mortgage is the size of the loan. When you buy through Co-Own, you are getting a mortgage on your share of the property, not the whole value³. On a 60% share of a £150,000 home, you need a mortgage on £90,000, not £150,000³. The trade-off is that you never stop paying for the part you do not own: rent to Co-Ownership continues until you buy that share out.

Co-Ownership's own illustration puts the monthly difference at £743 against £1,074. In its comparison example, a Co-Own buyer pays a £566 mortgage plus £177 rent, a total of £743, while buying the same home outright means a total monthly mortgage of £1,074¹. Those are illustrative figures from the scheme, not a quote for any particular buyer.

How Co-Own differs from a standard mortgage

With a standard mortgage you borrow the whole purchase price minus your deposit, and every payment reduces a debt secured on the entire property. With Co-Own you borrow only against your share. Co-Ownership owns the rest and charges you rent on it¹.

That split changes three things. First, the mortgage is smaller, so affordability tests apply to a smaller loan. Second, there are two payments each month rather than one: your mortgage to your lender, and rent to Co-Ownership on their share³. Third, you are not the sole owner. Co-Ownership's share is real ownership, not a loan, and it is bought back rather than repaid.

The share range is wider than in shared ownership elsewhere in the UK. Co-Own runs from 50% to 90%¹. In England the new national model for shared ownership runs from 10% to 75%, with reduced rent on the rest⁷, and older guidance describes shares usually between 25% and 75%⁹. Scotland's shared ownership schemes work differently again, with a mortgage payment for the share you own and a monthly occupancy charge¹⁰.

Co-Ownership also runs a separate product, Co-Own for Over 55s, where there is no mortgage involved: you buy a share of between 50% and 90% using savings or equity from your current home when you sell it¹.

Monthly costs compared: £743 with Co-Own against £1,074 on a full mortgage

Co-Ownership's own comparison example sets out the two monthly positions side by side. On the Co-Own side, a £566 mortgage plus £177 rent comes to £743. On the full ownership side, the total monthly mortgage is £1,074¹.

Those figures illustrate the shape of the difference rather than a rate. The mortgage element is smaller because you are borrowing less, and the rent element is the price of not owning the whole property. Co-Ownership describes monthly costs as the mortgage on the share you own, paid directly to your lender, rent to Co-Ownership on the share it owns, plus all your household bills and costs⁶.

For Co-Own for Over 55s, where there is no mortgage, monthly costs are made up of rent to Co-Ownership on its share, plus all your household bills and costs, just like any homeowner⁶.

Two things follow. The rent is not fixed forever in the way a repayment mortgage payment is broadly predictable, and buying more shares reduces it. Co-Ownership states that if you have a mortgage through Co-Own, you will still pay that until it is cleared, but you will no longer pay rent to Co-Ownership once you own the whole home⁶.

Deposit and mortgage size on a £170,000 home

The deposit question is where Co-Own changes the arithmetic most. Because you only mortgage your share, the deposit is calculated against that share rather than the full price.

Co-Ownership's worked example is a 60% share of a £150,000 home, needing a mortgage on £90,000 rather than £150,000³. Two unresolved illustrative figures for a £170,000 property also appear: a property value of £170,000 against £161,500, and a deposit of £943 against £8,500.

For comparison, on a standard mortgage the deposit is a percentage of the whole price. A 10% deposit on a £250,000 house is £25,000, and on a £350,000 house it is £35,000. A 15% deposit on a £250,000 house is £37,500, on a £300,000 house £45,000, and on a £350,000 house £52,500¹¹. Those figures date from 2020 and are given as illustrations of how deposit percentages scale, not as current market rates.

The effect is straightforward: a smaller mortgage means a smaller deposit requirement in cash terms, because the deposit is a percentage of the amount you are buying. There is a separate page on whether you need a deposit for Co-Ownership.

Who can use Co-Own instead of a standard mortgage

Co-Ownership is for people who cannot afford to buy a home outright². The Northern Ireland Co-ownership scheme is described in official guidance in exactly those terms¹².

Co-Ownership itself is clear about the limits of its role: it cannot give mortgage advice, though it can explain how the process works with Co-Own³. That matters because the mortgage itself is a separate transaction with a lender, and the lender's affordability rules apply to the loan on your share.

Where more than one person is buying, the usual joint-buying questions apply. You are both responsible for the whole loan if you have a joint mortgage, so you will have to discuss how to handle the repayments¹³. Sharing a mortgage means you have joint debts, and action can be taken against either of you¹⁴. Joint mortgages are usually shared by two people, but some lenders will allow up to four borrowers to share a mortgage¹⁵. Buyers should also check the legal difference between buying as joint tenants or as tenants in common¹⁵; tenancy in common is typically used by friends or relatives buying together¹⁵.

There is a separate page on buying a home with someone else, and on whether Co-Ownership is only for first-time buyers.

Property limits: up to £230,000 on new build homes

Co-Ownership sets maximum property values, and they differ between new builds and existing homes. The maximum property value is £230,000 for new build properties and £215,000 for existing properties⁴. A second property value limit of £230,000 is being introduced for new build properties alongside the existing £215,000 limit, to help more people buy a new build home⁵.

The two limits interact depending on the approval you hold. Up to £215,000, you will be offered a single property value that applies to both existing properties and new builds. Between £215,001 and £230,000, you can choose an existing property up to £215,000 or a new build property up to the property value shown on your approval⁵. The increased limit for new build homes includes homes only available through Co-Ownership, as well as other eligible new build homes up to £230,000⁵.

Co-Ownership buys new build homes anywhere in Northern Ireland⁴. New builds must have a suitable 10-year structural warranty, and existing properties under 10 years old must have the balance of their original structural warranty⁴. The home must have an Energy Performance Certificate⁴. You must declare any incentives you are offered by the seller or developer, and Co-Ownership may not agree to them⁴.

There are also property types Co-Ownership does not accept, including homes with no central heating, non-standard or unconventional construction, mobile homes or temporary structures, houses in multiple occupation, homes with an annex, homes with Japanese Knotweed, properties sold incomplete or "as is", underpinned or defective properties, homes with agricultural use restrictions, properties with a private water supply, and homes that do not front onto an adopted road⁴.

Service charges are capped in Co-Ownership's expectations: usually no more than £200 per year for a house and no more than £1,000 per year for an apartment⁴.

Buying more of your home: staircasing in 5% steps to full ownership

Buying more of your home is called staircasing, and with Co-Ownership you can do it in steps or buy Co-Ownership out completely, with no fixed timeline¹. You can buy in 5% steps or larger blocks, depending on what works for your finances⁶.

The 5% minimum is now the standard across shared ownership schemes. The minimum additional share purchase has been reduced from 10% to 5%¹⁶, and other staircasing transactions are reduced to a minimum of 5% rather than 10%⁷. In Northern Ireland, the House Sales Scheme allows you to increase your equity share in multiples of five per cent at any time¹⁷.

There is a practical route through remortgaging. When you remortgage, you can borrow additional funds to buy more of your home from Co-Ownership. Your monthly mortgage payment will increase, but your rent to Co-Ownership will decrease³. That is the trade at the heart of staircasing: more debt, less rent.

Take-up is modest. Around 4,000 to 5,000 shared owners a year staircase to full ownership⁷. Co-Ownership reports that in 2025/26, 770 customers bought additional shares to reach 100% ownership of their homes.

If you have a mortgage through Co-Own, you will still pay that until it is cleared, but you will no longer pay rent to Co-Ownership once you own the whole home⁶. There is more on staircasing: buying more shares in a shared ownership home.

Costs and responsibilities that stay with you either way

Some costs do not change with the ownership structure. Buying a home brings new and ongoing costs such as paying the mortgage, rates, repairs and service charges¹². Those apply whether you own 60% or 100%.

Repairs and service charges are the ones people underestimate. Co-Ownership's own expectations cap service charges at no more than £200 per year for a house and no more than £1,000 per year for an apartment⁴, but those are expectations about what is reasonable, not a limit on what you can be charged. On new builds, the building warranty will usually cover the cost of structural repairs in the first 10 or 12 years¹⁸.

If you have other debts secured on the home, such as a second mortgage, those creditors may be entitled to a share of the proceeds, but the debt to the mortgage lender is paid first¹⁹.

Where a partner lives in the home but is not on the mortgage, they may not be legally responsible for paying it but will probably need to ensure it is paid in order to protect their home²⁰. That is a common source of difficulty when relationships change. There is guidance on what happens to an owned home after separation and on finances after a death in the household.

If payments become difficult, speak to your mortgage lender, as they may be able to reduce your payments for a period or alter the way your mortgage is paid, for example interest only²¹. Most lenders will usually expect you to meet your regular mortgage repayments for at least six months before agreeing to capitalise arrears²². Possessions remain significantly below the long-term average²³.

When you sell or leave: how Co-Ownership's share is paid back

Selling a Co-Own home means settling two things: your mortgage and Co-Ownership's share. Co-Ownership's share is not a loan that you repay on a schedule; it is an ownership stake that is bought out when the property is sold or when you staircase to full ownership.

Co-Ownership's own sale process is not set out in detail, so the mechanics of valuation, fees and timescales should be checked with Co-Ownership directly. What is stated is that when you sell your property, the proceeds are split according to the ownership shares agreed in your lease²⁴. For example, if you own 60% and Co-Ownership owns 40%, and the property sells for £100,000, you receive £60,000 (minus any outstanding mortgage balance and fees) and Co-Ownership receives £40,000²⁴. There is a separate page on selling a shared ownership home.

What can be said is what happens to the money. If you have other debts taken out with your home as collateral, such as a second mortgage, those creditors may be entitled to a share of the proceeds, but the debt to the mortgage lender is paid first¹⁹. Your mortgage is cleared from the sale proceeds before Co-Ownership's share is settled.

If you are selling because of a change in circumstances rather than by choice, there are routes that do not involve selling at all. The Mortgage to Rent scheme in Wales, for example, means you would no longer own your own home and in most cases you would be given an assured or an assured shorthold tenancy²⁵. Mortgage rescue schemes exist for homeowners in difficulty²⁶.

If a lender takes possession and sells the home, the sale is handled by the lender²⁷. If you are being contacted about arrears, you can complain directly to a bailiff or enforcement agent if they are treating you unfairly or harassing you, and you can also complain to the creditor they work for, then take the complaint to the governing body if it is unresolved²⁸.

Where to get help and how to complain

Start with Co-Ownership itself on anything to do with the scheme, the share, the rent or the property criteria. On the mortgage, raise the complaint formally with the lender²⁹.

If a complaint about a mortgage is not resolved, the Financial Ombudsman Service can look at it. The ombudsman publishes quarterly complaints data: in the first quarter of 2025/26 it recorded 157 buy-to-let mortgage complaints, 23% of which were upheld³⁰. In the first quarter of 2026/27 it recorded 153 buy-to-let mortgage complaints³¹. Those figures cover the buy-to-let category and are given as an indication of complaint volumes, not of Co-Ownership specifically.

Free, impartial help is available. StepChange provides debt advice for homeowners and sets out the debt solutions available to people with a mortgage¹⁴. Shelter Cymru and Shelter Scotland provide housing advice, and Citizens Advice covers buying and selling a home²⁴. For anyone considering releasing equity from a home later in life, the Equity Release Council explains how those products work and what happens if you move into long-term care³².