The tax bill must be submitted to Parliament for approval by Tuesday, two days before Greece is due to receive a new €34 billion ($44.4 billion) rescue loan installment.
Earlier this week, the Bank of Greece confirmed government forecasts that the economy would contract by more than 6 percent this year, and by a further 4-4.5 percent next year. By the end of 2013, the economy is expected to have shrunk by 25 percent in six years.
The effects are most visible in the unemployment rate, which stood at just under 10 percent just before Greece's financial crisis began in late 2009. Since then, jobs have been vanishing at a pace of almost 1,000 a day.
The largest labor union, the GSEE, has predicted the jobless rate will reach 29 percent next year.
"According to our calculations, the recession next year will be between 5 and 5.5 percent ... The money being taken out of the economy due to higher (taxes) is driving the recession," Savvas Rombolis, head of labor research at the union, told private Skai radio.
"So more businesses will close, more people will lose their jobs, and fewer graduates will find work."