The income tax expense comprises:
Current tax expense601690
Adjustment in the current year in relation to prior years(143)(105)
The deferred tax (credit)/expense comprises:
Origination and reversal of temporary differences22(99)(70)
Adjustment in the current year in relation to prior years2211720
Total tax expense for the year476535
The total tax charge can be reconciled to the accounting profit as follows:
Total comprehensive income for the year2,5342,137
Total tax expense476535
Profit before tax3,0102,672
Income tax calculated at 20.75% (2014: 22.5%)625601
Effect of expenses not deductible4255
Effect of share-based deductions(88)(13)
Innovation related tax credits(77)
Change in UK tax rate(23)
Effect of adjustments in respect of prior years(26)(85)

The tax credit of £26,000 (2014: £35,000) shown within "exceptional and other items" on the face of the statement of comprehensive income, which forms part of the overall tax charge of £476,000 (2014: £535,000) relates to the items analysed in note 4.

The prior year current tax credits in respect of both 2015 and 2014 primarily relate to research and development tax credits. The prior year deferred tax charge in 2015 of £117,000 relates to the first time recognition of deferred tax in relation to capitalised development costs.

The Budget on 8th July 2015 announced that the UK corporation tax rate will reduce to 19% by 2017. The change in rates was not substantively enacted at the balance sheet date and therefore has not been reflected in the tax rates used for deferred tax purposes. The future rate reductions will affect the Group's future current tax charges.