Income taxes - Reconciliation of Effective Tax Rate (Details) - His Majesty's Revenue and Customs (HMRC) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
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| Income taxes | |||
| UK tax rate | 19.00% | 19.00% | 19.00% |
| Tax-exempt reimbursable tax credits included within pretax Research and development expense | 3.60% | 4.10% | 2.80% |
| Surrender of R&D expenditures for R&D tax credit refund | (10.50%) | (10.30%) | (8.40%) |
| Expenses not deductible | (0.30%) | (0.20%) | (1.40%) |
| Change in valuation allowances | (18.80%) | (31.80%) | (17.80%) |
| Change in tax rates | 13.70% | 4.10% | |
| Difference in tax rates | 5.50% | 4.40% | |
| R&D tax credits generated | 2.10% | 2.00% | 1.80% |
| Other | (2.10%) | (1.40%) | (0.10%) |
| Effective income tax rate | (1.50%) | (0.50%) | 0.00% |
| X | ||||||||||
- Definition Percentage differences between the current UK tax rate and the future UK tax rate which is applied to deferred tax assets. No definition available.
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pre-tax income (loss) from continuing operations attributable to permanent difference relating to reimbursable tax credits. No definition available.
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pre-tax income (loss) from continuing operations attributable to the surrender of R&D expenditures for R&D tax credits. No definition available.
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| X | ||||||||||
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the income tax rates. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to research and development expense. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Details
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