The need for senior care hasn't abated and states in which we have some of our highest concentration of properties are also states with the highest projected increases in the 80-plus population cohort over the next 10 years.
Last month, the federal public health emergency declaration related to the corona's pandemic was extended through April 20, keeping in place the temporary 6.2% increase in federal Medicaid matching funds, including the three-day hospital stay waiver.
In addition to the new stimulus package being negotiated, about $30 billion of prior earmarked aid remains unallocated, which will hopefully provide some incremental support to operators in the industry.
Fourth quarter rent and mortgage interest income collections were strong at 98%.
The rent credit is expected to have an approximate $530,000 impact on our 2021 GAAP revenue and an approximate $1.3 million impact on our 2021 FAD.
Next, I'll discuss our Senior Lifestyle portfolio, which is currently a main area of focus for us as we work to transition the 23 communities they have operated for LTC.
So far in the first quarter, we have transitioned 11 assisted living communities to two operators.
Total revenue declined $190,000 compared with last year's fourth quarter.
Mortgage interest income increased $226,000 due to the funding of expansion and renovation projects.
Interest expense decreased $490,000 due to lower outstanding balances and interest rates under our line of credit in the fourth quarter of 2020 and scheduled principal payments on our senior unsecured notes.
Property tax expense decreased $809,000, primarily due to the timing of Senior Lifestyle property tax escrow receipts and the payment of related taxes.
G&A expense increased $675,000 compared with the fourth quarter of 2019 due to the reimbursement of legal fees from Senior Care in the prior-year period as well as the timing of certain expenditures.
Income from unconsolidated joint ventures decreased $270,000 due to a dissolution in 2019 of a preferred equity investment in a joint venture, offset by two preferred equity investments we made in 2020.
During the fourth quarter of 2020, we recorded a $3 million impairment charge associated with a memory care community in Colorado operated by Senior Lifestyle, the impairment related to our release efforts of this property.
During the fourth quarter of 2019, we recognized a $5.5 million impairment charge related to the Senior Lifestyle joint venture.
Accordingly, we received liquidation proceeds of $17.5 million and recognized a loss on liquidation of unconsolidated joint ventures of $620,000.
During the fourth quarter of 2020, we recognized an additional loss of $138,000 related to the final liquidation of this unconsolidated joint venture.
In the fourth quarter of 2019, we recognized a $2.1 million gain from insurance proceeds related to a close skilled nursing center in Texas.
This property sustained hurricane damage and rather than rebuild it, we sold it and two other properties in the fourth quarter of 2019, resulting in a cumulative loss of $4.6 million.
We provided Senior Lifestyle deferred rent in the amount of $394,000 in April of last year.
As a result, we wrote off a total of $17.7 million of straight-line rent receivable and lease incentives related to this master lease and transitioned rental revenue recognition to a cash basis effective July 2020.
During the fourth quarter of 2020, we applied their letter of credit and deposits totaling $3.7 million to accrued second quarter 2020 rent receivable of $2.5 million and notes receivable of $125,000 with the remaining $1.1 million to third and fourth quarter 2020 rent.
At December 31, 2020, Senior Lifestyle's unaccrued delinquent rent balance was $1 million.
Net income available to common shareholders for the fourth quarter of 2020 increased by $5 million, primarily resulting from acquisitions and completed development projects, rent increases, lower interest expense, the prior year's loss on sale, and the fourth quarter of 2019's $5.5 million impairment charge.
Offsets included the $3 million impairment charge, decreased rent related to the Preferred Care property sales, abated and deferred rent net of repayment, a decrease in property tax revenue, the 2019 receipt of 2018 past due rent from Senior Care, and the fourth quarter 2019 gain from insurance proceeds.
NAREIT FFO per fully diluted share is $0.78 in the fourth quarter of 2020 and $0.81 in the prior-year fourth quarter.
Excluding the gain from insurance proceeds in the fourth quarter of 2019, FFO per fully diluted share was $0.76.
The $0.02 increase in FFO excluding the gain was due to lower weighted average shares outstanding in 2020, resulting from the purchase of shares in the first quarter of 2020 under our share buyback program.
Moving now to our investment activity, during the fourth quarter of 2020, we invested $5 million under our previously announced $13 million preferred equity commitment related to the development of a 267 unit independent and assisted living community in Vancouver, Washington.
Our investment earns an initial cash rate of 8% and a 12% IRR.
We expect to fund our remaining $8 million investment before the end of the first quarter of 2021.
We also funded $6.3 million in development in capital improvement projects at a weighted average rate of 8% on properties we own and paid $22.4 million in common dividends.
Our 2020 FAD payout ratio was 77%.
We currently have remaining commitments under mortgage loans of $1.7 million related to expansions and renovations on three properties in Michigan.
We also paid $7 million in regular scheduled principal payments under our senior unsecured notes.
Subsequent to the end of the quarter, we borrowed at $9 million under our unsecured line of credit.
Including this borrowing, we have $7.8 million in cash, $501.1 million available on our line of credit, under which $98.9 million is outstanding, and $200 million under our ATM program, providing LTC with liquidity of approximately $709 million.
At the end of the 2020 fourth quarter, our credit metrics remained favorably compared with the healthcare REIT industry average, with net debt to annualized adjusted EBITDA for real estate of 4.3 times and annualized adjusted fixed-charge coverage ratio of 5.3 times and a debt to enterprise value of approximately 30%.
We collected 98% of fourth-quarter rent and mortgage interest income including the application of Senior Lifestyle's letter of credit and deposit.
Of the rent not collected, $360,000 related to rent abatements and $369,000 related to rent deferral, net of repayment, which were provided to three private pay operators Clint mentioned on our previous earnings call.
As I mentioned earlier, Senior Lifestyle remains delinquent in their 2020 contractual rent by $1 million, and they have paid no rent so far in 2021.
For all of 2020, we collected 98% of contractual rent including the application of Senior Lifestyle's letter of credit and deposits.
Of the 2% we did not collect, 0.7% was abated, 0.7% was net deferred, and the remaining 0.6% was delinquent.
To date so far in 2021, rent deferrals totaled $689,000, net of $14,000 of deferred rent repayments.
Excluding the rent credit related to the rent escalation reduction already discussed, abated rent to date in 2021 is $360,000.
As Wendy said earlier, thus far in the first quarter of 2021, we have transitioned 11 of the 23 assisted living communities under their master lease.
Combined, these communities contain 344 units.
Incremental cash rent under the amended lease is $2.7 million for the first year, $3.7 million for the second year, and $3.9 million for the third year, escalating by 2% annually thereafter.
On February 15, we transferred five communities, all in Wisconsin with a total of 374 units to Encore Senior Living.
Encore, founded in 2011, is a major player in the Wisconsin market, operating 34 locations [Indecipherable] these communities.
Cash rent under the lease is $2.6 million for the first year, $3.3 million for the second year, and $3.4 million for the third year, escalating by 2% annually thereafter.
There are now 12 buildings remaining in the Senior Lifestyle portfolio.
The four remaining properties have a net book value of approximately $4.5 million.
As of February 15, occupancy was 23%, up from 10% on October 23.
We have agreed to provide them $1.3 million of additional free rent.
At February 15, occupancy was 64%, up from 23% on October 20.
In 2020, we extended a $4 million capital commitment to Brookdale, which is available through December 31, 2021, at a 7% yield.
To date, we have funded $2 million of this commitment.
Q3 trailing 12-month EBITDARM and EBITDAR coverage using a 5% management fee was 1.14 times and 0.94 times respectively for our assisted living portfolio.
Excluding Senior Lifestyle from our assisted living portfolio, EBITDARM and EBITDAR coverages would increase to 1.25 times and 1.04 times, respectively.
For our skilled nursing portfolio, EBITDARM and EBITDAR coverage was 1.85 times and 1.39 times, respectively.
Excluding stimulus funds, EBITDARM coverage was 1.58 times and EBITDAR coverage is 1.23 times.
Because our partners have provided January data to us on a voluntary and expedited basis, the information we are providing includes approximately 71% of our total private pay units and approximately 93% of our skilled nursing beds.
Private pay occupancy was 79% at September 30%, 72% at December 31, and 71% at January 31.
For skilled nursing, average monthly occupancy for the same time periods respectively was 70%, 66%, and 66%.

Summary:
NAREIT FFO per fully diluted share is $0.78 in the fourth quarter of 2020 and $0.81 in the prior-year fourth quarter.