BRASILIA, Aug 19 (Reuters) - Brazil's Senate approved a bill to roll back payroll tax breaks on Wednesday that is a key measure in President Dilma Rousseff's efforts to reduce a gaping fiscal deficit and restore confidence in her government's accounts.

The Senate voted 45-27 to pass the bill. It was received from the lower house with no changes, so it will go to Rousseff to be signed into law without delay.

The vote puts an end to months of heated debate over the final major piece of legislation in Rousseff's fiscal austerity plan aimed at saving Brazil's threatened investment grade credit rating.

(Reporting by Anthony Boadle; Editing by Lisa Shumaker)