If you’ve got any of the old five pound notes left, today is the day to spend them. On Friday the 5th of May, old fivers will cease to be legal tender.
As a business then you may well get lumped with a few fivers from your customers who are themselves desperate to get rid before they go out of circulation. In that case, your bank should still accept them for deposits for at least a few weeks. However from Friday you shouldn’t accept them in your shop or indeed any sort of business. You also shouldn’t try to palm them off to customers in their change. If you’re a customer and a business tries to give you an old fiver, you’re well within your rights to ask for a new fiver or coins instead.
The good news is that, although you won’t be able to freely spend old fivers (or any old notes), they never lose their face value. You can swap them for new currency at any point in the future, although that involves a trip to the Bank of England, Threadneedle Street, London (or popping them in the post at your own risk).