2019
2018
Deferred tax assets:
Reserves and accrued expenses
$    175.2
$    156.5
Inventories
4.3
4.5
Net operating loss carryforwards
111.2
67.9
R&D credits
4.1
6.1
Valuation allowance
(36.3)
(26.4)
Outside basis difference on investments held for sale
—
2.7
Lease liability1
64.0
—
Total deferred tax assets
$    322.5
$    211.3
Deferred tax liabilities:
Reserves and accrued expenses
$      15.5
$      14.3
Amortizable intangible assets
1,229.9
1,043.0
Plant and equipment
10.8
6.6
Accrued tax on unremitted foreign earnings
17.1
16.3
Outside basis difference on investments held for sale
—
10.0
ROU asset1
61.7
—
Total deferred tax liabilities
$ 1,335.0
$ 1,090.2
the deferred income tax balance sheet accounts arise from temporary differences between the amount of assets and liabilities recognized for financial reporting and tax purposes .
components of the deferred tax assets and liabilities at december 31 were as follows : .
[ 1 ] upon adoption of asc 842 deferred taxes associated with previously recognized deferred rent liabilities were reclassified into deferred taxes for rou asset and lease liability .
as of december 31 2019 the company had approximately $ 19 .
0 of tax-effected u .
s .
federal net operating loss carryforwards .
some of these net operating loss carryforwards have an indefinite carryforward period and those that do not will begin to expire in 2021 if not utilized .
the majority of the u .
s .
federal net operating loss carryforwards are subject to limitation under the internal revenue code of 1986 as amended - “ irc ” section 382 ; however the company expects to utilize such losses in their entirety prior to expiration .
the u .
s .
federal net operating loss carryforwards decreased from 2018 to 2019 primarily due to current year tilization .
the company has approximately $ 33 .
7 of tax-effected state net operating loss carryforwards -without regard to federal benefit of state .
some of these net operating loss carryforwards have an indefinite carryforward period and those that do not will begin to expire in 2020 if not utilized .
the state net operating loss carryforwards are primarily related to florida and new jersey but the company has smaller net operating losses in various other states .
the company has approximately $ 65 .
6 of tax-effected foreign net operating loss carryforwards .
some of these net operating loss carryforwards have an indefinite carryforward period and those that do not will begin to expire in 2020 if not utilized .
the foreign net operating loss carryforwards increased from 2018 to 2019 primarily due to the recognition of a discrete tax benefit of $ 41 .
0 in connection with a foreign restructuring plan allowing the future realization of net operating losses .
additionally the company has $ 5 .
0 of u .
s .
federal and state research and develop- ment tax credit carryforwards -without regard to federal benefit of state .
some of these research and development credit carry- forwards have an indefinite carryforward period and those that do not will begin to expire in 2020 if not utilized .
as of december 31 2019 the company determined that a total valuation allowance of $ 36 .
3 was necessary to reduce u .
s .
fed- eral and state deferred tax assets by $ 15 .
4 and foreign deferred tax assets by $ 20 .
9 where it was more likely than not that all of such deferred tax assets will not be realized .
as of december 31 2019 the company believes it is more likely than not that the remaining net deferred tax assets will be realized based on the company ’ s estimates of future taxable income and any applicable tax-planning strategies within various tax jurisdictions .

Question: How do the deferred income tax balance sheet accounts arise from?
Answer: temporary differences between the amount of assets and liabilities recognized for financial reporting and tax purposes