How to use it
Choose a wedding anniversary or a birthday, then put in the date. The answer shows straight away. Nothing you type is stored or sent anywhere.
If the day has already gone by, the tool checks whether you can still ask for a belated message. If you can't, it moves on to the next year that qualifies.
Which years qualify
For a couple, GOV.UK's list starts at 60 years married. Then comes 65, then 70, and from there every single year. For a birthday it starts at 100, then 105, and after that every year too. Silver, ruby and golden weddings are not on it.
How the dates are worked out
Online, the earliest you can apply is five weeks ahead, so the tool counts back 35 days. Late is allowed for half a year, so it also counts six months forward from the day. If a wedding or birthday was on 29 February, we use 28 February in other years. That last part is our choice: GOV.UK does not say.
For a birthday, you may not need to apply at all. GOV.UK says that if the person gets a State Pension or other benefit and lives in the UK, the message is sent using the name and address on that record.
We leave out postal dates on purpose. GOV.UK says three weeks before by post, but the Palace's own paper form says five, so we set out both in our guide to applying, along with what to do in Scotland and Northern Ireland.
Source
The rules are from GOV.UK, read on 30 October 2026. Our site checks that page every night, and the line under the tool says when it last matched. Contains public sector information licensed under the Open Government Licence v3.0.
Planning the party? Our anniversary countdown counts the days, and the diamond wedding page has ideas for the 60th.