What is Britain putting off that the next generation will pay for?

From the UKJP’s principles, 9. Future generations: government should be judged by the country it leaves behind, not only by the next election.

Which decision, taken or avoided for the sake of the next election, will cost those who come after us most? And what would make a government act on it before the bill arrives?

Any position may be argued here, including that the question is framed wrongly.