Estimates are that about 100,000 Portuguese have made use of the special relief on interest.
Tax officials say the average debts of people who have taken up the offer are in the region of 2,000 euros.
However, the Finance Ministry did admit some disappointment as it had expected larger debts to be settled.
The plan allows people with tax and social security debts to benefit from a partial or total pardon of interest and costs.
The programme closes on 20 December 2016 and taxpayers interested in it can register online on the Finanças Portal or at Social Security direct.
According to Dennis Swing Greene of Eurofinesco, individual taxpayers or businesses have to decide whether to make a one-off settlement or pay in installments (up to a maximum of 150 months).
The Government expects an annual increment of €100 million from the Special Debt Reduction Programme.