(Benefit) provision for income taxes. The benefit for income taxes for the nine months ended September 30, 2020 was $4.8 million, or -27.3% of income before income taxes, compared to a provision of $3.3 million, or 27.1% of income before income taxes for the nine months ended September 30, 2019. The effective tax rate in 2020 consisted principally of the 21% federal statutory tax rate, the recognition of research and development tax credits, the tax benefit from the loss carryback claim, the rate impact from state income taxes, the shortfall from share-based compensation, and permanent tax differences. The decrease in the effective tax rate for the nine months ended September 30, 2020 compared with the nine months ended September 30, 2019 is primarily attributable to the recognition of research and development tax credits for the current and prior years and a tax benefit from the loss carryback claim to a prior period with a higher statutory rate granted under the CARES Act, partially offset by a shortfall from share-based compensation.
We evaluate our deferred tax assets quarterly to determine whether adjustments to the valuation allowance are appropriate in light of changes in facts or circumstances, such as changes in expected future pre-tax earnings, tax law, interactions with taxing authorities, and developments in case law. Our material assumptions include forecasts of future pre-tax earnings and the nature and timing of future deductions and income represented by the deferred tax assets and liabilities, all of which involve the exercise of significant judgment. As of September 30, 2020, our valuation allowance approximated $2.1 million.
During the second quarter of 2020, we completed a study of qualifying research and development expenses resulting in the recognition of tax benefits of $2.2 million, net of tax reserves, related to the current year and $6.3 million, net of tax reserves, related to prior years as of the third quarter of 2020. We recorded the tax benefit, before tax reserves, as a deferred tax asset.
The CARES Act, which was enacted on March 27, 2020, includes changes to certain tax laws related to the deductibility of interest expense and depreciation. ASC 740, Income Taxes, requires the effects of changes in tax rates and laws on deferred tax balances to be recognized in the period in which the legislation is enacted. As a result of the CARES Act provisions, in the third quarter of 2020 we recognized a tax benefit of $4.0 million resulting from the loss carryback claim to a prior period with a higher statutory rate, which also decreased our current income taxes payable by $9.5 million as of September 30, 2020.
Financial Condition, Liquidity, and Capital Resources
Liquidity
Our cash and cash equivalents, and any amounts we have available for borrowing under our revolving credit facility, are immediately available to provide cash for our operations and capital expenditures. We refer to the sum of these two amounts as our “liquidity.”
At September 30, 2020, we had total liquidity of $242.3 million, which reflected an increase of $73.1 million from the $169.2 million in liquidity we had as of December 31, 2019. Our liquidity at September 30, 2020 was comprised of cash and cash equivalents of $147.5 million and $94.8 million in available borrowing capacity under our $100.0 million revolving credit facility. This increase in liquidity primarily related to an increase in cash of $73.1 million, comprised of net cash provided by operations of $125.2 million, which includes approximately $24.0 million in Grants from the federal government under the CARES Act, partially offset by investing cash flows for purchases of property plant and equipment, and purchases of therapeutic program equipment, of $22.5 million, cash paid for acquisitions, net of cash acquired, of $16.9 million, and net cash used in financing activities of $14.1 million. As of September 30, 2020, we have repaid in full all $79.0 million in borrowings under our revolving credit facility.
Our Credit Agreement contains customary representations and warranties, as well as financial covenants, including that we maintain compliance with certain leverage and interest coverage ratios. If we are not compliant with our debt covenants in any period, absent a waiver or amendment of our Credit Agreement, we may be unable to access funds under our revolving credit facility. Due to the additional borrowings under our revolving credit facility in March 2020, which were repaid in full during the third quarter of 2020, and in anticipation of the potential economic impact of the COVID-19 pandemic, we entered into an amendment to the Credit Agreement that provided for, among other things, increases in the allowable level of indebtedness we may carry relative to our earnings, changes in the definition of EBITDA used to compute certain financial ratios, certain restrictions regarding investments and payments we may make until the completion of the first quarter of 2021 and increases in the interest costs associated with borrowings under our revolving credit facility. We were in compliance with our debt covenants as of September 30, 2020.