The federal savings and loan insurance fund has paid Columbia First Federal Savings & Loan $15 million in cash and may pay Meritor Savings Bank $100 million because of a recent ruling against a special bookkeeping technique used by the regulators.

The Financial Accounting Standards Board, the organization that sets national bookkeeping standards, had ruled in April that certain notes issued by the Federal Home Loan Bank Board no longer could count as assets of an S&L.

The bank board regulates thrifts and insures thrift deposits. Last year, it issued $15 million in notes to Columbia First, the District's largest S&L, and $100 million in notes to Meritor of Arlington so that the two institutions could boost their net worth, which is the difference between assets and liabilities. The thrifts received the notes in exchange for buying ailing thrifts and taking them off the government's hands.

The bank board created the notes rather than making a direct cash payment in the hope of stalling a cash drain on the federal fund, which insures thrift deposits up to $100,000. The fund has been strained in recent years by record failures of savings and loans.

Last week, Columbia announced that the bank board had agreed to replace its notes with $15 million in cash. Meritor said yesterday that it is considering the tax effect of converting its notes to cash. Income earned from the cash could be taxed, a Meritor spokesman said.

The ruling by the accounting standards board affected a bank board policy that permitted notes -- called income capital certificates -- to be counted as permanent funding.

Under the note program, the bank board gives a troubled S&L a promissory note that it can count as an asset under bank board accounting standards, which are more liberal than those used by the Securities and Exchange Commission and by most companies.

The theory is that the notes buy time for a sick thrift to get back on its feet and might never have to be paid. In the case of Columbia and Meritor, the bank board went a step further by permitting notes to be counted as permanent funding and an asset under generally accepted accounting principles. The accounting board and the SEC disagreed and told the S&Ls to replace the notes with cash or wipe them off their books.