People are less enthusiastic about the third phase of the Taste, Shop, Spend scheme than the previous two phases, says Finance Minister Uttama Savanayana.
The lacklustre response is acceptable as the third phase is an extension, he said.
"We are not surprised and already planned for a smaller response in the third phase," said Mr Uttama.
"The scheme needs to be evaluated overall, not just a particular phase. Our intention is to give the economy a jolt in the arm."
Last week, the cabinet approved the third phase of the scheme. Some 2 million new registrants are eligible, of which 500,000 spots have been allotted for the elderly.
Unlike the previous two phases, the third offers a cash rebate for spending at participating merchants anywhere in Thailand, including recipients' home provinces, while those who sign up for the third phase are no longer eligible for the 1,000-baht cash handout.
The third phase also allows those who buy tour packages, air tickets and lodging for domestic travel to take part in the scheme. Recipients receive 15% cash back for spending of up to 30,000 baht at participating merchants, and the rebate rises to 20% for 30,001 to 50,000 baht spent, with up to 8,500 baht available as cash back.
All phases of the scheme will end in January because the government aims to boost domestic expenditure until the Chinese New Year.
Lavaron Sangsnit, director-general of the Fiscal Policy Office, said 90,000 elderly people have signed up for the third phase since registration opened on Nov 17.
The Finance Ministry has not set a closing date for registration for the elderly as it reserved a quota of 500,000 registrants for the third phase. The government does not expect the elderly will be as active as the general population in registering, said Mr Lavaron.
The elderly as a group are not as sophisticated using technology as younger generations, so the ministry delegated Krungthai Bank (KTB) to facilitate registration for older Thais, he said.
The Finance Ministry last week said 11.6 million of the 13 million recipients for the first two phases completed the registration process, and 11.4 million spent the 1,000-baht cash giveaway.
Recipients of the scheme's first two phases have spent 12.4 billion baht, of which 12.3 billion came from the 1,000-baht cash giveaway and the remaining 100 million via the 15-20% cashback scheme through KTB's Pao Tang G-wallet 2 app.
To be eligible for the cash handout and the 20% cash rebate of up to 50,000 baht for tourism-related spending, Thais aged 18 and older were required to sign up at the Taste, Shop, Spend website and download the Pao Tang mobile app.
The spending scheme is part of the government's 316-billion-baht stimulus package, aimed at boosting the country's economic growth to 3% this year after the economy lost momentum.