The government has extraordinary power to collect student loans. The government can seize tax refunds, deny new student loans and grants, garnish wages without a court order, take a portion of Social Security benefits, and charge very large collection fees.
Most crimes can only be prosecuted for limited periods of time, but there is no time limit for collection on federal student loans.
Collection efforts begin soon after you miss a payment. The collection tactics get worse the longer you fail to pay. The most severe consequences kick in only if you default.
It is difficult, although not impossible, to be completely protected from government student loan collection. You will most likely be safe from collection only if you do not have significant federal benefits or wages, you do not get a tax refund, and you do not have any other collectible assets. Even if you are safe from collection now, this situation may be only temporary. Because there is no time limit on government student loan collections, the debt may still come back to haunt you in the future.
Private student loan collection is different. There is a time limit for collection and private collectors do not have as many collection tools as the government. This does not mean that private student loans are better than government loans. In fact, federal loans are usually more affordable and have important borrower protections.