Senior banking executives have informed the BBC that they anticipate the financial sector will be subject to new taxation measures in the Chancellor's upcoming Budget announcement. This expectation follows a period of significant profitability for the UK's largest banks.

Chancellor John Healey has referred to banks as vital components of the UK's economic infrastructure, but has not ruled out the possibility of increased taxes on the sector. This comes as the four largest banks collectively reported approximately £15 billion in profits during the first half of the current year, prompting calls from various groups for additional taxation.

UK Finance, the banking sector's trade body, has cautioned that further tax increases could negatively impact the industry's competitiveness, deter investment and job creation, and undermine the government's stated objective of fostering economic growth nationwide.

The UK's largest banks and building societies currently face a 3% surcharge on the standard 25% corporation tax rate, in addition to a levy on their balance sheet assets. Last year, the banking sector contributed close to £40 billion to the Treasury, a figure that includes income tax paid by employees. The bank levy alone generated £1.4 billion, with the surcharge adding another £1.2 billion.

Several potential avenues exist for the Chancellor to increase revenue from the sector. Reinstating the surcharge to its previous level of 8% from the current 3% could potentially generate around £2 billion annually. The bank levy, which taxes outstanding short-term loans at 0.1% and longer-dated loans at 0.05% (excluding mortgages), could also be adjusted.

Banks have historically argued that higher taxes could make the UK less competitive internationally and reduce their lending capacity, thereby hindering economic growth. Many in the sector were surprised they were not targeted in the previous Budget, given their recent strong financial performance, which has been bolstered by rising interest rates widening the gap between lending and savings rates.

An alternative proposal involves a temporary moratorium on banks using past losses to offset current profits, a practice that reduces their tax liabilities. This measure is estimated to yield an additional £1 billion per year for the Treasury. This approach is viewed by some industry figures as a more 'bearable' form of windfall tax.

Such a move could also mitigate additional burdens on foreign banks operating in the UK, including JP Morgan. The chief executive of JP Morgan has previously warned that the UK already imposes a high tax burden on banks and that further sector-specific taxes could deter investment and harm competitiveness. However, industry leaders also note that any tax increase disproportionately affecting UK banks while exempting foreign operations could conflict with the government's support for domestic businesses.