With just a month left for Americans to select health plans this year through new insurance marketplaces, the Obama administration is bending some rules to prevent people from being stranded without coverage, especially those in states where their own state-run online exchange has failed disastrously. The new policy applies to people who — because of “technical issues” — were prevented in trying to buy insurance through an online exchange and signed up for a health plan outside the marketplace. They will now be allowed to sign up for coverage in the exchange and get federal subsidies “on a retroactive basis,” going back to the date on which they first enrolled in a health plan outside the exchange. The state-run exchanges in some of these states — Oregon, Maryland, Massachusetts and Hawaii in particular — have experienced more technical problems than even the federal website. Consumers in those states are still having difficulty enrolling five months after the launch. Federal officials said they had agreed to provide such assistance retroactively because technical problems had prevented consumers from using online exchanges to obtain insurance and financial aid in some states. The Obama administration’s decision came as a surprise because the Affordable Care Act is clear: Federal subsidies are available only to people who enroll in a “qualified health plan” through an exchange. The HHS change will allow those who tried to sign up on their state-run exchanges, but couldn’t, to retroactively obtain the subsidies they would have been eligible for, even if they ended up purchasing healthcare through a private insurer. The privately purchased plans must still meet certain basic requirements of the healthcare law.