Is this legal? A company advises its workers to submit their payclaims for their wages within 3 months. An employee forgets and hands it in on the 4th month as they forgot some extra work they did. Result - the employer refuses to honour these extra work wages. Can they do this?

If it is not part of the regular standard payment as detailed in their contract (eg it is overtime, bonus, travel claims, commission etc), I would guess the employer may have not to pay it - 3 months sounds a reasonable period. I've come across rules like this before and can't recall any serious challenge, but I can recall a few p*ssed off people.

Obviously if there are extenuating circumstances then you would expect a bit of leeway - eg if the person was on sick leave, abroad etc.

Note that variable payments cannot be called "wage", a wage is a regular payment.

Above is purely my opinion.

Best asking Citizens Advice or Trade Union (or possibly ACAS)

Can't find an email to explain the above for ACAS - only their telephone number.

RE: ACAS ..... A lot of places like this don't give out their email address because its so difficult to sort out the genuine emails and the spam.

Liverpool office details ...

Redgrave Court
Merton Road
Bootle
Merseyside
Liverpool
L20 7HS
United Kingdom
Tel: 08457 383 736