In the six months since the IMF last provided its economic forecasts, the situation in Spain has gone from bad (but sustainable) to worse (and unsustainable). Their current forecasts show no 'peak' in debt-to-gdp ratios at least as far as 2018 with the budget deficit primarily to blame.
As Bloomberg Briefs notes, general government primary borrowing, a measure that excludes the cost of paying interest on government debt, was revised up to 7.9% of GDP from 4.5% for 2012.
The inability to narrow the budget deficit, surprise surprise, appears partially due to lower real GDP growth forecasts and even then a recent study has found that World Economic Outlook real GDP growth forecasts showed a tendency to systematically exceed outcomes. This phenomenon was particularly prevalent in countries with an IMF-supported program.
The IMF warns Spain "will need to undertake unprecedented fiscal efforts to bring their debt ratios to traditional norms," as most countries have never experienced debt levels similar to current ones; and seemed to think a debt restructuring is more likely and will "entail substantial and long-lasting economic and social costs."
Source: @Davidjpowell24 and Bloomberg Briefs