(12) Income Taxes:

The following is a reconciliation of the provision for income taxes computed at the federal statutory rate to income taxes computed at the effective rate:



	For the three months ended
	March 31,

	2019		2018

Consolidated tax provision at federal statutory rate	21.0	%	21.0	%
State income tax provisions, net of federal income
tax benefit	(3.2)		7.2
Remeasurement of certain deferred tax balances	-		(11.9)
Tax reserve adjustment	(0.9)		1.2
Changes in certain deferred tax balances	(38.6)		14.2
Shared-based payments	(4.4)		10.6
Federal research and development tax credit	1.7		(2.0)
All other, net	(1.6)		0.8
Effective tax rate	(26.0)	%	41.1	%

As of December 31, 2018, amounts pertaining to expected income tax refunds of $1.5 million and $1.5 million are included in “Income taxes and other current assets” and “Other assets” in the consolidated balance sheets, respectively.

Frontier considered positive and negative evidence in regard to evaluating certain state net operating loss carryforwards during the first quarter of 2019, including the development of recent years of pre-tax book losses. On the basis of this evaluation, a valuation allowance of $34 million ($27 million net of federal benefit) has been recorded on the deferred tax assets related to these state NOL carryforwards and reflected in “Changes in certain deferred tax balances”. The amount of the deferred tax asset considered realizable, however, could be adjusted if estimates of future taxable income during the carryforward period are reduced or increased or if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as our projections for growth.