... don't assume that means you don't have to - call them and check.
This (which may be completely a one-off, but just in case not) has just happened to me. I called, out of curiosity, because I normally spend January in tax-return stress-mode; and lo and behold, I've been "unaccountably omitted" from the list of those sent a tax return for 2007/2008 - although, indeed yes, I do need to do one. One is being sent to me now.
Note: I get 3 months from the date I get it to complete it, and no £100 fine on 31 January etc. But I wonder what would have happened if I'd waited till after 31 Jan to call?
Hence - if you are in this position - CALL BEFORE 31 JAN.