Saudi Arabia and the United Arab Emirates, which have long lured foreign workers with the promise of a tax-free lifestyle, plan to impose a 5% tax next year on most goods and services to boost revenue after oil prices collapsed three years ago.
The value-added tax, or VAT, will apply to a range of items like food, clothes, electronics and petrol, as well as phone, water and electricity bills, and hotel reservations.
Elda Ngombe, a 23-year-old college graduate who is looking for a job in Dubai, said there is one specific purchase she is planning before next year's price hike:
"Make-up, because I can't live without make-up."
"I am scared because everything is actually expensive already in Dubai. The fact that it's actually adding 5% is crazy," she said.
There will be some exemptions for big-ticket costs like rent, property sales, certain medications, airline tickets and school tuition.
Higher education, however, will be taxed in the UAE.
Extra costs parents pay to schools for uniforms, books, school bus fees and lunch will also be taxed, as will property brokerage costs for renters and buyers.
Other Gulf countries are expected to implement their own VAT scheme in the coming years.
Stores, gyms and other retailers are trying to make the most of the remaining tax-free days in Saudi Arabia and the UAE, encouraging buyers to stock up before the VAT is rolled out on January 1 2018.
Even with a 5% jump in prices, the tax rate is still significantly less than the average VAT rate of 20% in some European countries.
"If you compare with Europe, I don't think it's as expensive. Only in rent and food," said Vera Clement, a mother and assistant manager of restaurants from France who has lived in Dubai for three years.
"We are going to be more careful when we buy something," she added.
The National newspaper, based in Abu Dhabi, says the cost of living in the UAE is expected to rise about 2.5% next year because of the VAT.
Salaries, meanwhile, remain the same.
As the government adjusts to lower oil prices, the UAE is expected to raise around 12 billion dirhams ($3.3bn) from the tax.
Meanwhile, Saudi Arabia recently unveiled the biggest budget in its history, with plans to spend 978 billion riyals ($261bn) this coming fiscal year as the government forecasts a boost in revenue from the introduction of VAT and plans to reduce subsidies.
Still, Saudi Arabia is facing a budget deficit until at least 2023.
The International Monetary Fund has recommended oil-exporting countries in the Gulf introduce taxes as one way to raise non-oil revenue.
The IMF also recommends Gulf countries introduce or expand taxes on business profits.
IMF Mideast director Jihad Azour said VAT is part of a long-term tax reform to help Gulf states reduce their dependence on oil revenues.
"It is something that will allow the government to diversify revenues," he said on the sidelines of an event in Dubai, adding that any immediate slowdown in spending by consumers next year will be compensated for with government investments.
In line with IMF recommendations, Saudi Arabia and the UAE this summer imposed a 100% tax on tobacco products and energy drinks, and a 50% tax on soft drinks.
VAT, however, is by far the most wide-ranging tax to be rolled out in the two countries.