The Conservatives have promised to look "very closely" at proposals for wide-ranging tax cuts, including the abolition of inheritance tax.
Mr Osborne has promised to make economic stability the priority
A party policy group also recommends reducing business taxes and raising the threshold for higher rate income tax.
Shadow chancellor George Osborne said he could not "offer an upfront, overall reduction" at the next election, but he would look at a "range of options".
But Labour said the proposals would create a financial "black hole".
The Conservatives' Competitive Challenge working group said rising house prices meant too many people are paying 40% inheritance tax, which applies to estates worth more than £300,000.
To boost the economy, it also said corporation tax - payable on business profits - should be cut from 30p in the pound to 25p for large firms, and to 20p for small firms.
The group, led by former Cabinet minister John Redwood, recommended that the point at which people pay the higher - 40% - rate of income tax should be raised under a Tory government.
It also said capital gains tax should not be paid on any asset held for more than 10 years.
Mr Osborne offered broad support for the plan to cut corporation tax, while he said scrapping inheritance tax was one of a "range of options" he was considering.
He added that he would look at all Mr Redwood's proposals, but said: "We will not be able to offer an upfront, overall reduction in tax at the general election.
"Any reduction in specific taxes will have to be balanced by tax increases elsewhere, most notably 'green' taxes."
The policy group is one of several set up by party leader David Cameron, but its findings do not have to be adopted as policy.
Since last autumn Mr Osborne has promised the Conservatives will put economic stability ahead of tax cuts.
'Proceeds of growth'
This stance has been criticised by several prominent figures within the party, including former chairman Lord Tebbit.
Mr Redwood said his proposals would not require cuts in public services because they would help the economy grow.
He added: "They're paid for out of the proceeds of growth.
"The shadow chancellor has rightly said he will share that money. Some of that money should go to improve public services and some of it can go to tax reductions."
Inheritance tax is not currently payable on 94% of estates, according to official figures.
The £300,000 threshold is due to increase to £350,000 by 2010, which the government says will ensure this remains the case.
Chancellor Alistair Darling said the Conservatives were "lurching to the right".
He told the BBC: "What the Tories are proposing is actually £21bn of tax reductions, but they don't say how they are going to pay for them."
Liberal Democrat Treasury spokesman Vince Cable said: "This report shows that David Cameron's Conservative party is stuck in Thatcherite Britain."
The proposals would "widen the divide between rich and poor", he added.