£ Millions20182017
Singapore corporation tax:
– current year3.53.1
– over-provision in prior financial year(0.2)(1.5)
Overseas corporation tax:
– current year3.32.6
– under/(over)-provision in prior financial year0.3(0.4)
Current income tax6.93.8
Deferred income tax
– current year0.31.1
– change in tax rate(1.3)
Income tax expense7.23.6

Taxation for other jurisdictions is calculated at the rates prevailing in the respective jurisdictions at the balance sheet date.

In 2017, the United States of America ("USA") Government announced changes to the USA tax laws, which reduces the federal tax rate from 35% to 21% with effect from financial year 2018. The deferred tax expense for the financial year ended 31 December 2017 had taken into consideration the change in the federal tax rate which resulted in a reduction of deferred tax liability by £1.3 million.

In 2017, the financial year 2014, 2015 and 2016 Singapore tax assessment was finalised, there was an approximate tax credit of £1.3 million to be recoverable from the Singapore tax authority. In 2018, £1.7 million was refunded by the Singapore tax authority.

The differences between the total income tax expense shown above and the amount calculated by applying the standard rate of Singapore income tax rate to the profit before income tax are as follows:

£ Millions20182017
Profit before income tax37.632.2
Tax on profit at standard Singapore tax rate of 17% (2017: 17%)6.45.5
Tax incentives(0.5)(0.9)
Higher rates of overseas corporation tax1.12.0
Deduction for employee share options(0.2)0.2
Non-deductible expenditure0.3
Adjustment in respect of prior year0.1(1.9)
Change in tax rate(1.3)
Income tax expense 7.23.6

Movement in corporate tax recoverable:

£ Millions20182017
At 1 January2.9
Currency translation differences0.2
Income tax payable
– current year(2.5)
– (under)/over-provision in prior financial year(0.1)1.5
Income tax paid2.01.4
Refund received(1.7)
At 31 December0.82.9

Movement in current income tax liabilities:

£ Millions20182017
At 1 January(3.5)(3.3)
Currency translation differences(0.2)0.4
Income tax paid3.84.7
Income tax payable
– current year(4.3)(5.7)
– over-provision in prior financial year0.4
At 31 December(4.2)(3.5)

There is no (2017: £nil) tax (charge)/credit relating to components of other comprehensive income.

Aggregate deferred tax asset arising in the reporting period and not recognised in net profit or loss or other comprehensive income but directly (debited) or credited to equity:

£ Millions20182017
Deferred tax asset – share option plan expenses(0.9)1.1