Table:
| Company - 2018 | Provisions | Others | Total |
| --- | --- | --- | --- |
| Deferred tax assets | S$ Mil | S$ Mil | S$ Mil |
| Balance as at 1 April 2017 | 0.3 | 2.8 | 3.1 |
| Effects of adoption of SFRS(I) 15 | - | (1.0) | (1.0) |
| Balance as at 1 April 2017, restated | 0.3 | 1.8 | 2.1 |
| Credited to income statement | 0.2 | 9.0 | 9.2 |
| Balance as at 31 March 2018 | 0.5 | 10.8 | 11.3 |
|  |  | Accelerated tax |  |
| Company - 2018 |  | depreciation | Total |
| Deferred tax liabilities |  | S$ Mil | S$ Mil |
| Balance as at 1 April 2017 |  | (285.3) | (285.3) |
| Effects of adoption of SFRS(I) 1 |  | 10.2 | 10.2 |
Paragraphs:
Notes: (1) TWDV – Tax written down value
(2) NBV – Net book value
Deferred tax assets and liabilities are offset when there is a legally enforceable right to set-off current tax assets against current tax liabilities, and when deferred income taxes relate to the same fiscal authority.
Question:
When is it allowed to offset deferred tax assets and liabilities?