Dave, Typically the DTA's are brought back on the balance sheet giving a nice bump to net worth. It is a paper asset that is used against future tax liabilities. I forgot what Fannie's amount of DTAs Fannie recognized last quarter but let's say it was $50 bil. That in itself raised Fannie's shareholder's equity by $50 bil. There was NO liability to offset it.
The PSPA calls for the net worth over $3 bil to be sent to the treasury. This quarter that $50 bil is sent to the treasury. Not as a paper asset but in cash. The balance sheet is reduced by $50 bil. In essence the value of DTA has been monetized and sent away. Sure, it still sits on the balance sheet as an asset to be used against future tax liabilities, but now it is has been "funded" with debt.
$50 bil DTA = Plus $50 bil to balance sheet $50 bil paid to UST = Minus $50 bil from balance sheet
$50 bil new debt = new liability
Your little formula does not account for the $50 bil paid out. Aren't you in accounting?