In the US, it's not a crime as long as you file your taxes accurately. The IRS generally allows you to set up a payment plan or even settle for less than is owed if it would cause hardship to pay.

Right, but you DO need to file the tax returns with the IRS, accurately reporting your income, and then actually negotiate the payment plan (and stick to it or renegotiate).

We don't just get to unilaterally declare that 'I'll be uncomfortable paying taxes, so it can wait'... and then not bother to file or negotiate a plan, which seems to sum up OP's position. Wish him/her luck, they'll need it!

Concealing income is a crime, delaying payment is not (though you will pay penalties and interest). It's quite easy to get a payment plan where you do this and don't risk garnishment or other collection efforts as long as you follow it.

As others said, as long as you're being transparent to authorities on how much you owe, it's typically not a crime - but it will likely attract interest and extra fees, possibly at punishing levels (depending on how you go about it).

In the end, it's in the interest of the State, like any other creditor, that you don't actually die of starvation (or worse). Getting a continued stream of money, even if smaller than you expected, is better than getting no money at all.

Who cares if it's not enforced? Granted, IRS does enforce, but apparently they take their time about it.

It's a crime only in US. Most civilized countries allows people to stagger their taxes.