Table of Contents At December 31, 2019, approximately $1,320 million of U.S. state tax net operating losses (NOLs) and $125 million of U.S. state tax credit carryforwards were available. The state NOLs primarily expire over the next twenty years. The state tax credit carryforwards primarily expire over the next fifteen years, with some credits having an unlimited carryforward period. In total, we have established a valuation allowance of $172 million related to certain of these carryforwards. At December 31, 2019, approximately $264 million of U.S. foreign tax credits were available for carryforward. These credits expire in 2028. At December 31, 2019, amounts and expiration dates of net operating loss and interest carryforwards in various non-U.S. taxing jurisdictions were: At December 31, 2019, non-U.S. entities that have not yet demonstrated consistent and/or sustainable profitability to support the realization of net deferred tax assets have recorded valuation allowances of $750 million, including certain entities in Luxembourg. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for uncertain tax positions, including positions impacting only the timing of tax benefits, follows. 93 (Millions of dollars) 2020 2021 2022 2023-2025 2026-2040 Unlimited Total $ 104 $ 53 $ 81 $ 59 $ 451 $ 3,627 $ 4,375 The components of deferred tax assets and liabilities were: December 31, (Millions of dollars) 2019 2018 Deferred income tax assets: Tax carryforwards $ 1,218 $ 1,312 Postemployment benefits other than pensions 876 793 Pension 445 785 Warranty reserves 263 237 Research expenditures 219 — Allowance for credit losses 171 155 Post sale discounts 200 158 Other employee compensation and benefits 197 186 Lease obligations 157 — Stock-based compensation 107 121 Other—net 250 298 4,103 4,045 Deferred income tax liabilities: Capital and intangible assets, including lease basis differences (1,574) (1,381) Bond discount (122) (127) Translation (194) (190) Other outside basis differences (257) (271) Undistributed profits of non-U.S. subsidiaries (118) (129) (2,265) (2,098) Valuation allowance for deferred tax assets (928) (915) Deferred income taxes—net $ 910 $ 1,032