How are unmarried couples taxed on capital gains?

The main difference between married and unmarried couples for the purposes of Capital Gains Tax is that unmarried couples can't take advantage of the exemption for interspouse transfers. Married couples are free to transfer assets between themselves without incurring a CGT charge. If you're an unmarried couple this does not apply. Note that there is no concept of commonlaw marriage for tax purposes. Therefore even if you've been together for 40 years, you still won't qualify for the exemption. As such a transfer between unmarried couples would crystallise a capital gain, with the proceeds likely to be deemed to be market value (if it's not an arms length transaction). In terms of claiming Principal Private Residence relief on a disposal of a main residence, unmarried couples can in certain circumstances be at an advantage. Married couples need to have the same main residence, however unmarried couples don't. Therefore if you own two properties unmarried couples could secure a CGT exemption by arranging for each partner to occupy one of the properties.