This very much depends on the wording in your shared ownership lease and if you live in a house or flat.
The following is therefore only a general guide and you should check the detail of your specific lease.
House – You will generally be responsible for meeting all the costs of any repairs and maintenance regardless of what share size you own.
Flat – You will generally be responsible for meeting the costs of any repairs and maintenance of the internal elements of your flat. For example, the decoration, flooring, internal doors, plasterwork, servicing your boiler, fixing plumbing leaks, and handling electrical repairs.
The outside of your flat and any communal areas are usually the responsibility of the housing association who will normally seek to recover the costs of such works through any service charge.
Initial Repair Period – Since 2021 some shared ownership leases include a clause that requires the housing association to refund up to £500 per year (for the first ten-years) to help cover essential internal repairs (like plumbing and heating fixtures). You should check that this cover applies to your lease and the housing association’s specific policy before committing to any expenditure.