Plans for a UK ISA might be over already due to objections from PM Rishi Sunak and his staff at No 10.
Chancellor Jeremy Hunt floated the idea of a tax wrapper that would allow investors exclusively to put money into UK stocks.
Details leaked recently suggested it would mean a £5,000 rise in the tax-free allowance to £25,000 if the extra money goes into UK businesses.
Sources close to the PM, however, were reported saying that it is not the government’s job to tell people how to invest their money.
Any changes also would not come into force until well past the next election, where polls suggest the government is on course to lose heavily.
Tory MPs want more immediate measures such as tax cuts and action to ease the cost of buying a house to try to turn the polls around.
Hunt will deliver a pre-election Budget on March 6, where he is expected to have around £20bn to hand out based on recent economic and tax receipt forecasts.
ISA providers reportedly are not keen on the UK ISA idea either due to the additional complication and complexity that would be involved.
Susannah Streeter, at wealth platform and ISA provider Hargreaves Lansdown, reflected the sceptical view.
A separate British ISA might end up providing no additional boost to UK investment, she said.
“Those who already max out their £20,000 ISA allowance could simply hive off all their existing UK holdings to the British ISA, and use the extra wiggle room to invest more overseas in their usual ISA,"
Alternatively, boosting the overall ISA investment allowance would likely do the same without limiting the potential for diversification and without adding another layer of rules, Streeter added.