WWYD? Christmas bonus

[Thingsthatgo]

I woke in a really small business, just 2 employees.
For the last 4 years my boss has given me a cash bonus at Christmas. He just gave it to me in an envelope on my last working day before Christmas.
This year he didn't. But he is notoriously forgetful, and it's been a good year at work, and I did something pretty spectacular for the business in November.
So I think he just forgot. Can I ask him?
I won't be seeing him again until January. My DM says to just keep using the word 'bonus' when talking to him, in the hope it'll trigger his memory!

The other employee is new, so she is no help to me!

yes, I declare it through my self assessment.
Not really what I was asking, but important none-the-less!

Nothing wrong with asking. It isn't an entitlement but it has become a reasonable expectation so fair enough to ask. He has the discretion to give it or not, but if you don't ask, you'll never know. Some people are funny about money discussions but isn't that the whole point of employment and busineses generally? For future years, I also wouldn't hesitate to discuss what was needed to position you for the maximum bonus. Do you know what the maximum is? In some industries, the minimum and maximum bonus amounts for a pay grade are part of the general conversation.

Do you know if anyone else got a bonus?

There is nothing wrong with asking politely, but personally I would first check with the other employee (if you have a good relationship with them), and I would wait until the first couple of days back in Jan before asking (in case has indeed forgotten).
I wouldn't bother my manager on holiday unless it's an emergency/critical for the business.