Restructuring charges During the year we incurred charges of £386m (2017/18: £241m, 2016/17: £nil), primarily relating to leaver costs. These costs reflect projects within our group-wide cost transformation programme and include costs related to the remaining integration of EE and £23m costs to close the BT Pension Scheme and provide transition payments to affected employees.
EE integration costs EE integration costs incurred in prior years (2017/18: £46m, 2016/17: £215m) relate to EE related restructuring and leaver costs. In 2016/17, this also included a £62m amortisation charge relating to the write-off of IT assets as we integrated the EE and BT IT infrastructure. In the current year remaining EE integration activities have been combined into the wider restructuring programme.
Retrospective regulatory matters We have recognised a net charge of £27m (2017/18: £49m, 2016/17: £479m) in relation to regulatory matters in the year. This reflects the completion of the majority of compensation payments to other communications providers in relation to Ofcom’s March 2017 findings of its investigation into our historical practices on Deemed Consent by Openreach, and new matters arising. Of this, £31m is recognised in revenue offset by £4m in operating costs.
Pension equalisation costs During the year we recognised a charge of £26m (2017/18: £nil, 2016/17: £nil) in relation to the high court requirement to equalise pension benefits between men and women due to guaranteed minimum pension (GMP).
Property rationalisation costs We have recognised a charge of £36m (2017/18: £28m, 2016/17: £nil) relating to the rationalisation of the group’s property portfolio and a reassessment of lease-end obligations.
Italian business investigation During the year we have released £(55)m provisions relating to settlement of various matters in our Italian business (2017/18: a charge of £22m, 2016/17: a charge of £238m).
Interest expense on retirement benefit obligation During the year we incurred £139m (2017/18: £218m, 2016/17: 209m) of interest costs in relation to our defined benefit pension obligations. See note 20 for more details. Tax on specific items A tax credit of £112m (2017/18: £87m, 2016/17: 154m) was recognised in relation to specific items.
10. Specific items continued EE acquisition warranty claims In the prior year we reached settlements with Deutsche Telekom and Orange in respect of any warranty claims under the 2015 EE acquisition agreement, arising from the issues previously announced regarding our operations in Italy. This represents a full and final settlement of these issues and resulted in a specific item charge of £225m.
Table:
10. Specific items continued |  |  | 
 | 2019 | 2018 | 2017
Year ended 31 March | £m | £m | £m
Revenue |  |  | 
Italian business investigation | – | – | 22
Retrospective regulatory matters | 31 | 23 | (2)
 | 31 | 23 | 20
Operating costs |  |  | 
EE acquisition warranty claims | – | 225 | –
Restructuring charges | 386 | 241 | –
EE integration costs | – | 46 | 215
Property rationalisation costs | 36 | 28 | –
Pension equalisation costs | 26 | – | –
Retrospective regulatory matters | (4) | 26 | 481
Italian business investigation | (55) | 22 | 238
Out of period irrecoverable VAT | – | – | 30
Profit (loss) on disposal of businesses | 5 | (1) | (16)
 | 394 | 587 | 948
Operating loss | 425 | 610 | 968
Net finance expense |  |  | 
Interest expense on retirement benefit obligation | 139 | 218 | 209
Interest on out of period irrecoverable VAT | – | – | 1
 | 139 | 218 | 210
Net specific items charge before tax | 564 | 828 | 1,178
Taxation |  |  | 
Tax credit on specific items above | (112) | (87) | (154)
Tax credit on re-measurement of deferred tax | – | – | (63)
 | (112) | (87) | (217)
Net specific items charge after tax | 452 | 741 | 961


Question: What was the pension equilisation cost related to?
Answer: high court requirement to equalise pension benefits between men and women due to guaranteed minimum pension (GMP).