At May 31, 201 9 , we had federal net operating loss carryforwards of approximately $ 732 million, which are subject to limitation on their utilization. Approximately $ 690 million of these federal net operating losses expire in various years between fiscal 2020 and fiscal 2018 . Approximately $42 million of these federal net operating losses are not currently subject to expiration dates. We had state net operating loss carryforwards of approximately $ 2.2 billion at May 31, 2019 , which expire between fiscal 2020 and fiscal 2018 and are subject to limitations on their utilization. We had total foreign net operating loss carryforwards of approximately $ 2.0 billion at May 31, 2019 , which are subject to limitations on their utilization. Approximately $ 1.9 billion of these foreign net operating losses are not currently subject to expiration dates. The remainder of the foreign net operating losses, approximately $ 100 million, expire between fiscal 2020 and fiscal 2019. We had tax credit carryforwards of approximately $ 1.1 billion at May 31, 2019 , which are subject to limitations on their utilization. Approximately $ 734 million of these tax credit carryforwards are not current ly subject to expiration dates. The remainder of the tax credit carryforwards, approximately $ 387 million, expire in various years between fiscal 2020 and fiscal 2019
We classify our unrecognized tax benefits as either current or non-current income taxes payable in the accompanying consolidated balance sheets. The aggregate changes in the balance of our gross unrecognized tax benefits, including acquisitions, were as follows:
As of May 31, 2019, 2018 and 2017, $4.2 billion, $4.2 billion and $3.4 billion, respectively, of unrecognized tax benefits would affect our effective tax rate if recognized. We recognized interest and penalties related to uncertain tax positions in our provision for income taxes line of our consolidated statements of operations of $312 million, $127 million and $125 million during fiscal 2019, 2018 and 2017, respectively. Interest and penalties accrued as of May 31, 2019 and 2018 were $1.3 billion and $992 million, respectively.
Domestically, U.S. federal and state taxing authorities are currently examining income tax returns of Oracle and various acquired entities for years through fiscal 2017. Many issues are at an advanced stage in the examination process, the most significant of which include the deductibility of certain royalty payments, transfer pricing, extraterritorial income exemptions, domestic production activity, foreign tax credits, and research and development credits taken. With all of these domestic audit issues considered in the aggregate, we believe that it was reasonably possible that, as of May 31, 2019, the gross unrecognized tax benefits related to these audits could decrease (whether by payment, release, or a combination of both) in the next 12 months by as much as $516 million ($357 million net of offsetting tax benefits). Our U.S. federal income tax returns have been examined for all years prior to fiscal 2010 and we are no longer subject to audit for those periods. Our U.S. state income tax returns, with some exceptions, have been examined for all years prior to fiscal 2007 and we are no longer subject to audit for those periods.
Internationally, tax authorities for numerous non-U.S. jurisdictions are also examining returns affecting our unrecognized tax benefits. We believe that it was reasonably possible that, as of May 31, 2019, the gross unrecognized tax benefits could decrease (whether by payment, release, or a combination of both) by as much as $186 million ($87 million net of offsetting tax benefits) in the next 12 months related primarily to transfer pricing.
Table:
 |  | Year Ended May 31, | 
(in millions) | 2019 | 2018 | 2017
Gross unrecognized tax benefits as of June 1 | $5,592 | $4,919 | $4,561
Increases related to tax positions from prior fiscal years | 772 | 200 | 128
Decreases related to tax positions from prior fiscal years | (135) | (65) | (218)
Increases related to tax positions taken during current fiscal year | 540 | 840 | 595
Settlements with tax authorities | (153) | (42) | (85)
Lapses of statutes of limitation | (202) | (273) | (47)
Cumulative translation adjustments and other, net | (66) | 13 | (15)
Total gross unrecognized tax benefits as of May 31 | $6,348 | $5,592 | $4,919


Question: How does oracle classify its unrecognized tax benefits?
Answer: We classify our unrecognized tax benefits as either current or non-current income taxes payable in the accompanying consolidated balance sheets