We reported funds from operations or FFO of $17.5 million or $0.16 per share for the fourth quarter of 2020 and $79.4 million or $0.74 for the year ended December 31, 2020.
During the fourth quarter, we worked with tenants that were impacted by the pandemic and had a significant write-off of one large tenant that filed for bankruptcy in late December that resulted in a $3.1 million charge against our revenue.
During Q4, we had write-offs and lost rent of about $3.1 million which is primarily from a tenant bankruptcy that I noted and on a year-to-date basis, the total write-offs were about $3.8 million or about 1.5% of our annual rental income.
The total of rents deferred by us during Q4 were about $300,000 and for the year totaled about $1.75.
These agreements generally result in us being repaid or made whole -- with the whole -- as part of the $1.75 million we did occur about $200,000 of GAAP and FFO impact from them this year.
Turning to our balance sheet at December 31, '20, we had $923.5 million of unsecured debt, excluding [Phonetic] $3.5 million drawn on our line of credit.
In December, we sold a property in North Carolina for $89.7 million and applied $87.3 million of the proceeds against debt.
With the proceeds from the sale, we applied $50 million against $150 million term loan that matures in November and the remainder one against the drawn balance of our line of credit.
At year-end, between cash on hand and availability on our line, we had total liquidity of about $601 million.
We disclosed some ratios in our supplemental filing that were impacted by the $3.1 million write-off we incurred in late December.
Excluding this charge, our net debt-to-EBITDA ratio would have been 7.8 times compared to 8.5 times at September 30 and that decrease would be primarily a result of the debt reduction.
Our interest and debt service coverage ratios were also impacted and would have been 3.26 times.
We disclose our calculations of ratios in our supplemental filing and the calculations I'm referring to are in the footnotes on Pages 4 and 10 in case you're interested in looking at them.
As a reminder, all of our debt is unsecured and we have no debt maturities until November when $155 million of term loans will be due.
Our debt is at fixed rates other than the $3.5 million on the line which is at a floating rate.
We believe that users of office space are now reconsidering the office densification trends of the past approximately 20 years.
Accordingly, we have introduced full-year 2021 disposition guidance in the range of approximately $350 million to $450 million in aggregate gross proceeds.
At the end of the fourth quarter, the FSP portfolio including redevelopment properties was approximately 83.8% leased which is a decrease from 84.3% leased at the end of the third quarter.
The average leased occupancy of the portfolio for calendar 2020 was approximately 83.6%.
FSP leased approximately 1.130 million square feet during calendar 2020, which included 368,000 square feet of new leases and approximately 150,000 square feet of expansions with existing tenants.
During the fourth quarter, we finalized over 500,000 square feet of renewals and expansions with existing tenants.
FSP is currently tracking approximately 700,000 square feet of potential new leases and renewals.
There are approximately 300,000 square feet of new tenant prospects that have shortlisted FSP properties.
In addition, we are engaged with existing tenants for approximately 400,000 square feet of renewals.
Barring any surprises, the potential for total net absorption over the next three months to six months is approximately 200,000 square feet.
The third will be to build upon our December 23 sale of Emperor Boulevard with additional but select dispositions, estimated to be in the range of $350 million to $450 million for full-year 2021 and then to utilize such proceeds primarily for the repayment of debt in order to gain greater financial flexibility and to position FSP for stronger shareholder returns.
Proceeds from potential dispositions under review are currently estimated to be in the range of $350 million to $450 million for full-year 2021, which again would be intended primarily to be used for the repayment of debt.

Summary:
We reported funds from operations or FFO of $17.5 million or $0.16 per share for the fourth quarter of 2020 and $79.4 million or $0.74 for the year ended December 31, 2020.
Accordingly, we have introduced full-year 2021 disposition guidance in the range of approximately $350 million to $450 million in aggregate gross proceeds.
The third will be to build upon our December 23 sale of Emperor Boulevard with additional but select dispositions, estimated to be in the range of $350 million to $450 million for full-year 2021 and then to utilize such proceeds primarily for the repayment of debt in order to gain greater financial flexibility and to position FSP for stronger shareholder returns.
Proceeds from potential dispositions under review are currently estimated to be in the range of $350 million to $450 million for full-year 2021, which again would be intended primarily to be used for the repayment of debt.