* Annual budget target at risk
* Net debt/GDP ratio falls slightly to 35 pct
BRASILIA, Dec 28 (Reuters) - Brazil's government posted a deficit of 5.515 billion reais ($2.7 billion) in November, the central bank said on Friday, putting the government's primary fiscal target for 2012 in serious jeopardy.
The primary budget data is a gauge closely watched by investors because it measures a country's ability to service its debt. It represents the excess of revenue over expenditures before interest payments are taken into account.
With Friday's result, the primary surplus reached 82.7 billion reais in the year, compared with 126.8 billion reais for the same period in 2011.
The government has said it will resort to alternative accounting methods to meet its primary surplus target of 139.8 billion reais this year. That accounting maneuver will allow the government to reduce the fiscal target by 25.6 billion reais.
Still, to reach the adjusted target the government will need to post a primary surplus of 31.5 billion reais in December.
The primary surplus in the 12 months through November equaled 1.93 percent of Brazil's gross domestic product, down from 2.25 percent in the prior month, while the public debt-to-GDP ratio edged down to 35 percent from 35.2 percent in October.
A sharp slowdown in tax revenues and a string of tax breaks provided by the government to lift a sluggish economy have dragged down primary savings this year, though a widely expected rebound in economic growth next year should help the government recover some ground.
"In the fiscal area, we are expecting a slightly better primary surplus as a proportion of GDP in 2013 than this year," wrote Octavio de Barros, chief economist with Bradesco in Sao Paulo, in a report last week. "This is mainly due to the resumption of the growth of economic activity which should more than offset the tax exemptions."