Deferred Taxes The components of the net deferred tax liability are as follows:
Deferred income taxes are provided for the temporary differences between assets and liabilities recognized for financial reporting purposes and assets and liabilities recognized for tax purposes. The ultimate realization of deferred tax assets depends upon taxable income during the future periods in which those temporary differences become deductible.
To determine whether deferred tax assets can be realized, management assesses whether it is more likely than not that some portion or all of the deferred tax assets will not be realized, taking into consideration the scheduled reversal of deferred tax liabilities, projected future taxable income and tax-planning strategies.
Consolidated and its wholly owned subsidiaries, which file a consolidated federal income tax return, estimates it has available federal NOL carryforwards as of December 31, 2019 of $349.5 million and related deferred tax assets of $73.4 million.
The federal NOL carryforwards for tax years beginning after December 31, 2017 of $60.7 million and related deferred tax assets of $12.8 million can be carried forward indefinitely. The federal NOL carryforwards for the tax years prior to December 31, 2017 of $288.8 million and related deferred tax assets of $60.6 million expire in 2026 to 2035.
ETFL, a nonconsolidated subsidiary for federal income tax return purposes, estimates it has available NOL carryforwards as of December 31, 2019 of $1.0 million and related deferred tax assets of $0.2 million. ETFL’s federal NOL carryforwards are for the tax years prior to December 31, 2017 and expire in 2021 to 2024.
We estimate that we have available state NOL carryforwards as of December 31, 2019 of $758.5 million and related deferred tax assets of $16.7 million. The state NOL carryforwards expire from 2020 to 2039. Management believes that it is more likely than not that we will not be able to realize state NOL carryforwards of $80.3 million and related deferred tax asset of $5.2 million and has placed a valuation allowance on this amount.
The related NOL carryforwards expire from 2020 to 2037. If or when recognized, the tax benefits related to any reversal of the valuation allowance will be accounted for as a reduction of income tax expense.
The enacted Tax Act repeals the federal alternative minimum tax (“AMT”) regime for tax years beginning after December 31, 2017. We have available AMT credit carryforwards as of December 31, 2019 of $1.5 million, which will be fully refundable with the filing of the 2019 federal income tax return in 2020.
We estimate that we have available state tax credit carryforwards as of December 31, 2019 of $7.7 million and related deferred tax assets of $6.1 million. The state tax credit carryforwards are limited annually and expire from 2020 to 2029.
Management believes that it is more likely than not that we will not be able to realize state tax carryforwards of $1.8 million and related deferred tax asset of $1.5 million and has placed a valuation allowance on this amount. The related state tax credit carryforwards expire from 2020 to 2024. If or when recognized, the tax benefits related to any reversal of the valuation allowance will be accounted for as a reduction of income tax expense.
Table:
 | Year Ended December 31, | 
(In thousands) | 2019 | 2018
Non-current deferred tax assets: |  | 
Reserve for uncollectible accounts | $1,194 | $1,164
Accrued vacation pay deducted when paid | 4,152 | 4,371
Accrued expenses and deferred revenue | 9,839 | 12,848
Net operating loss carryforwards | 86,535 | 76,659
Pension and postretirement obligations | 80,245 | 84,786
Share-based compensation | 693 | 9
Derivative instruments | 5,868 | (825)
Financing costs | 176 | 189
Tax credit carryforwards | 6,077 | 6,411
 | 194,779 | 185,612
Valuation allowance | (6,680) | (9,158)
Net non-current deferred tax assets | 188,099 | 176,454
Non-current deferred tax liabilities: |  | 
Goodwill and other intangibles | (66,271) | (82,992)
Basis in investment | (5) | (12)
Partnership investments | (16,138) | (14,425)
Property, plant and equipment | (278,712) | (267,154)
 | (361,126) | (364,583)
Net non-current deferred taxes | $(173,027) | $(188,129)


Question: What determine whether deferred tax assets can be realized or not realized?
Answer: taking into consideration the scheduled reversal of deferred tax liabilities, projected future taxable income and tax-planning strategies.