Comment Wind them up (Score 1) 341
Depends on the jurisdiction of your invoice. In the UK it's a 222 winding-up order (ask your accountant).
In practice (and I've had to do this myself) you get your lawyer to send them a letter stating that they are in default, that you are to petition the High Court for a 222 winding up order, and that you will call a creditors meeting which will be advertised in the national press. Unless you get immediate payment by return of post.
What got me, was that it didn't even affect my relationship with the client. Their accountants just smirked and said "Ah, you've found out how to get us to pay then". It was like a game to them. Oh, and they sent a man on a motorbike with the money, not even a cheque, so that I had to explain to my bank why I was depositing such a large amount of cash (in the UK, unusual cash deposits are queried and reported to the police).