> In the US, if a payment is "available" to you, it must be reported as income at the time it becomes available. Failure to cash a paycheck doesn't mean you don't owe tax on it.

I don't believe that's correct. A check which is never cashed is not income, as the funds are never transferred there is no income, there is no income tax. The point of the IRS regulation is that tax period in which the check is received is the applicable one, rather than the tax period when it is cashed.