If it’s a bad check then here in RI the police will accompany you to collect, on duty as part of their job. I don’t think they have any authority to act, but witnessing the act of refusal to pay is supposed to lead to more serious action from a prosecutor. I believe it clarifies the intent to defraud.
The more we discuss the problems with collecting on a court order, the more I want to take my $600 and be happy for it. Which is complete bullshit, because people should pay their bills after you do work for them, but they know that they will make your life a living hell if you try to collect through the court systems. 
But it could just as easily be that the debtor believes that they have a valid reason not to pay, not an intent to defraud. (eg goods not delivered on time, work not done as specified in the contract, etc. (Not saying any of that is the case here, of course. 
) Police here don’t get involved in civil debt enforcement, for just those reasons. They’re familiar with the criminal law, not civil law.
I worked for a guy who had the sheriff show up at work one day and start seizing his assets.
It’s not common for police to get involved in any civil matter in the US, and this is an exception in RI, possibly just an old tradition. I’m sure people who have good reason to dispute a payment are in the clear, this practice I am pretty sure was intended to focus on real deadbeats. As I noted, I don’t think a police officer can do anything except intimidate, and I suppose he might as easily be a witness to a valid disputation of the debt.
The sheriff in Canada is not part of the police. Sheriffs are the civil enforcement officer for the courts, who enforce a judgment once it’s been properly registered with the court.
As in the USA, except that in the USA some (but not all) sheriffs still also responsible for policing.
You must buy this? Really?
I am not a expert in Canadian tax law, but unless you have already including this as income , there is no such thing.
However- can you tell us WHY he wont pay you? Because if his story is halfway decent, and if Canadian Small Claims courts judges are like those in the USA, you might not win.
Cat_Whisperer has pointed out that she is acting on the advice of her accountant, who presumably is familiar with Canadian tax law.
Yes, good point. Still, my question remains.
You can in Canada.
Very good point. I overlooked that the OP is in Canada.
Maybe send a letter or two reminding them that it could be turned over to a collection agency and see what happens (without actually doing the deed).
Sorry, I wasn’t clear - I was agreeing with you. 
Our collection department will go after debts much less than $1,000. While most of their calls I overhear are to consumers, our company sends business credit data to Experian and Equifax. Our members who send their commercial accounts receivable do report derogatory information; either simply through aging (days beyond terms), or with an actual code for Collections, Legal involvement, etc. (There are also codes for good payers.) A derogatory line on a credit report affects the debtor’s credit rating. This means that a company that has done business with you and has not paid, may not be able to get favourable credit terms when they borrow again, or may be refused credit.
While your company may be too small to report your monthly accounts receivable to a credit agency, the threat of reporting and the repercussions therefrom may be enough to induce payment. I’m not familiar with our credit reporting department, but from what I’ve overheard a non-payer does get dinged on their credit report.
Reading this thread, the testosterone-driven, dick-swinging toxic male in me wants you to screw these guys over hard, punish them for disrespecting you, grunt grunt chest pound.
The more sensible, mature part thinks that taking the tax benefit and lesson learned, and just walking away, is the more intelligent choice. Chalk it up to experience, and, as you said, take steps so that this doesn’t happen again.
Then go on to scientology dot com and sign your ex-client up for a free personality test.
Does this actually preclude you from going after your debtor for payment? If it does not, you can get your $600 today and still go after this guy for money owed.
That’s a good question - it sounds like a debt that has been written off is closed, but I can see that you might address a collection after you’ve written a debt off by putting it back into reported income.
I know I’m late to the game and post #60 is not likely to be read…But…
I’d suggest taking them to small claims court for only one reason…the education you will get out of it will be worth the $100. You can learn the process and become comfortable with it so that when it becomes a more necessary thing you will be better prepared for a future situation.