the Company has required approximately $7,000 per month to maintain its mineral claims in British Columbia in good standing and pay general administrative expenses. We believe these expenses can be maintained at present levels for the foreseeable future. Going forward, as a fully-reporting company, we estimate it will cost an additional $2,500 to $5,000 per month in SEC compliance fees, consisting primarily of accounting, legal, and edgarization fees. The Company believes it can generate enough revenue from claim sales and joint-ventures to cover these costs, and we believe we can rely on our equity credit line established with Tangiers to make up for any revenue shortfall. If we cannot generate sufficient revenue or raise additional funds through equity, we may not be able to maintain our mineral claims or make timely filings with the SEC.
In the first quarter of 2015, our mortgage on the Ruby Mine property requires us to make payments in aggregate of $60,000 per month, consisting of $20,000 on the 1st of each month, and an additional $40,000 by the 20th day of each month. As of December 31, 2014, the balance due on the mortgage is $1,697,055. The Company believes it can rely on revenue from claims sales and joint ventures, and from loans and our equity credit line established with Tangiers to make up for any revenue shortfall. If we cannot generate sufficient revenue or raise additional funds through equity or loans, we may not be able to maintain our mortgage on the Ruby Mine.
As of December 31, 2014, total current assets were $98,580, which consisted of $32,060 in cash, $1,515 in receivables, $31,049 in net deferred financing costs, and $33,956 in available for sale securities. As of December 31, 2013, total current assets were $179,339, which consisted of $133,873 in cash, $22,966 in net deferred financing costs, and $22,500 in available for sale securities.
As of December 31, 2014 and 2013, our total current liabilities were $5,418,662 and $3,383,679, respectively. The net increase in current liabilities is primarily due to an increase in the current portion of the Ruby Mine mortgage.
We had a working capital deficit of $5,320,082 as of December 31, 2014, and a working capital deficit of $3,204,340 as of December 31, 2013.
During the year ended December 31, 2014, operating activities used cash of $1,482,655 as compared to the twelve months ended December 31, 2013, where we used cash of $1,301,762 in operating activities. The increase in cash used by operating activities for the twelve months ended December 31, 2014 was due primarily to construction, rehabilitation, and exploration expenditures at the Ruby Mine.
