A will records decisions about who should receive your estate and who should administer it. It is worth revisiting the document when your circumstances change, even if you do not expect to make a major revision.
Changes that merit a review
Marriage, separation, a new child, a death in the family, or a significant change in property or business interests can all affect whether the existing document still reflects your intentions. The same is true if an executor or beneficiary can no longer take the role you expected.
Keep the signed version clear
Do not write changes onto a signed will. Ask how to make a valid update or replacement, then make sure the people who need to find the document know where the current signed version is kept. A professional can help where family or tax circumstances are complex.
For the current signing requirements in England and Wales, see GOV.UK's guide to making a will.