David Wood, of the Institute of Chartered Accountants of Scotland (Icas), made the claim as the professional body published a report setting out the context ahead of the referendum in June.
Voters across the UK will be asked to decide if the country should remain part of the EU or if it should leave.
The net cost of being in the EU amounted to £8.5 billion in 2015, with this the equivalent of £131 per person - or about 2.6 per cent of the average amount of income tax paid by UK taxpayers, the report said.
But £223 billion of exports go from the UK to Europe, more than two-fifths (44 per cent) of all exports and significantly higher than the £95 billion of goods sold to the US and £16 billion that go to China.
These exports are linked to more than three million jobs, Icas said, about 10 per cent of the total UK labour market.
The report said: “UK membership of the EU provides easier access to EU national economies, free movement of goods and no trade or tariff barriers.
“Other EU countries took 44 per cent of all UK exports in 2015 and provided 53 per cent of all UK imports. These exports sustained over three million UK jobs, around 10 per cent of the total UK workforce.
“It should be noted that the UK would still continue to trade with the EU if it voted to leave EU membership but this would be under new trade deals under terms which would need to be agreed.”
Almost half (48 per cent) of foreign investment into the UK comes from Europe, totalling £496 billion in 2014, Icas said.
Mr Wood said: “The cost of the UK contribution to EU budget (2015) was £8.5 billion (£17.8 billion gross less rebate of £4.9 billion and public sector receipts to UK of £4.4 billion).
“This represents 0.5 per cent of the UK’s estimated total GDP of £1.79 trillion for 2015.
“This illustrates that the fiscal aspect of the UK’s relationship with the EU, while important, is dwarfed by the significance of the UK/EU trading relationship, and regardless of the outcome of the vote it is critical that this is maintained.”