The cost of a will depends on the type of will you need. A simple will is likely to cost around £100 -£200 for an individual will and £150 - £300 for a mirror will. (Mirror wills are similar documents created on behalf of a married, civil partnership or unmarried couple. They are virtually identical wills where one member of the couple leaves their estate to other in the event of their death.) However if you need a more complex will, that includes a trust to manage the ongoing provision for family members, then it is likely to cost more.