The prime minister has ditched the 2015 pledge not to raise income tax or national insurance in the Conservative's election manifesto.
Her predecessor David Cameron had previously committed to a five-year "tax lock" not to raise income tax, National Insurance or VAT.
As she set out a vision for dealing with the "five great challenges" of the coming years, Theresa May promised there would be no increase in VAT over the next parliament.
But she left Chancellor Philip Hammond - who previously hinted that he would like to drop the 2015 tax pledge - flexibility to raise other taxes.
Mrs May also confirmed corporation tax will fall to 17% by 2020.
The Tories will "keep tax as low as possible" and simplify the system, according to its manifesto.
It also pledged to conduct a "full review of the business rates system to make sure it is up to date for a world in which people increasingly shop online".
The party also promised to "legislate for tougher regulation of tax advisory firms" and to take a "more proactive approach to transparency and misuse of trusts".