They go out of date.
WHAT CHANGES
Your delivery areas and costs Your returns period
The services you use: analytics, gateways, email platforms
Your business details The law
WHEN TO UPDATE
Whenever you change something they describe.
Adding an email marketing platform means your privacy notice should mention it.
Changing courier means your delivery page needs revising.
THE ANNUAL REVIEW
Read them once a year as though you were a customer.
You will find things that are no longer true.
WHAT PEOPLE FORGET
A privacy notice listing an analytics provider they stopped using Delivery timescales from before the courier changed A phone number that changed Prices in terms that are no longer current
DATING THEM
State when they were last updated. It signals maintenance and helps if a question arises about what applied when.
TELLING CUSTOMERS
For significant changes affecting existing customers, tell them rather than quietly amending.
For a small business, a note in your newsletter or a notice on the site is proportionate.
WHAT NOT TO DO
Write them once and never look again.