You should definitely look at your companies expenses policy to see what they will and will not cover. If it is not clear from that then put it down but be totally clear what it was and why you had to buy it. The worst they can do then is say no. If you try to hide it then you are open to dismissal and possibly criminal prosecution. My company has a zero tolerance policy on fraud and anyone caught deliberately manipulating their expenses will be dismissed and prosecuted (A high price to pay for a $13 umbrella).