Plaid Cymru has set out in its manifesto how it wants Wales to have control of its economic levers.
Party leader Rhun ap Iorwerth said at a UK level big corporations, including oil and gas and energy companies, should pay more tax than those with less means.
The party is in opposition in the Welsh Parliament and currently holds three of the 40 Welsh seats in UK parliament.
Launching the manifesto in Cardiff today (June 13), Iorwerth said: "We can influence the change coming, keeping the incoming Labour government in check not giving them a free pass for taking Welsh votes then casting Welsh interests aside."
The party said it would re-introduce a cap on bankers’ bonuses and would would investigate increasing higher earners’ national insurance contributions.
It would also support the introduction of a wealth tax and abolish non-dom tax loopholes.
Iorwerth committed to keeping the triple-lock pension increase.
The manifesto read: "We recognise that many in receipt of the state pension have no other way of increasing their fixed level of incomes, and believe that this increase – the highest of inflation, average earnings increase, or 2.5 per cent - is the fairest way of ensuring that their income keeps pace with the real world costs.
"We will also increase the income tax personal allowance for pensioners in line with the triple lock."
David Phillips, an associate director at the Institute for Fiscal Studies said despite the pledges made by the party it is not a given that tax devolution would result in more funding for Wales.
He said: "The latest estimates are that Wales receives about 20 per cent more for devolved services than is spent on comparable services in England.
"The last assessment of needs commissioned by the Welsh Government - admittedly 15 years ago - found needs were 14 per cent to 17 per cent higher than England. If this remained the case, a needs-based system could see funding for the Welsh Government reduced by around £1bn a year.
"Plaid Cymru’s preference for needs-based funding does not extend to areas in which a population-based allocation would mean more money for Wales. This includes funding for rail investment and policing; crime is lower in Wales than in England.
"Many spending pledges relate to areas controlled by the Welsh Government, including ambitions for free personal care, free childcare from 12 months, and free school meals for all secondary school children. Given the funding outlook, such measures would likely require the Welsh Government to make cuts elsewhere or increase taxation.
"Some spending pledges would require change at the UK level or further devolution. This includes increasing child benefit by £20 per week per child. This would cost around £600 to £700mn per year in Wales, which if undertaken at a devolved level, would be roughly equivalent to 2 per cent on all rates of income tax in Wales."
