Most property you own jointly — such as a bank account or your home — is not treated as part of your estate when you die. Instead, it automatically passes directly to the surviving owner. These items do not need to be included in your will, although you may wish to include them in case this changes in the future.
However, check that you don’t jointly own any assets as ‘tenants in common’ — where each of you owns a share of the asset. If you do, your share does form part of your estate and will pass under your will. For example, you may have bought a house with a partner and own it in proportion to the amount you contributed to the purchase price and the mortgage payments. You can each leave your share to whoever you want in your will.