* Public U.S. banks have about $134 bln in DTAs

* Writedowns likely to mostly hit smaller banks

* For some banks, writedowns can trigger capital raises (Corrects figure from billion to trillion in paragraph 6)

By Dan Wilchins

NEW YORK, Nov 13 (Reuters) - U.S. regulators are looking hard at banks' expected future tax benefits and the result for some financial institutions could be more writedowns.

Any charges are much more likely to hurt regional and community banks, than the largest U.S. lenders, who have more ways to preserve the benefits, known as "deferred tax assets," or DTAs.

The most common reason for a bank to write down these assets is an expected lack of taxable income in the future. As income becomes less likely, regulators including the Federal Deposit Insurance Corp are pressing banks to write them down, experts told Reuters.

Regulatory pressure often means that, at the margin, accountants are inclined to be much more conservative when evaluating these assets.

"As long as the FDIC is looking at this, writedowns will be much more widespread," said Jim Goeller, a partner at tax firm Perry-Smith in San Francisco, which audits more than 60 banks in California. An FDIC spokesman said the agency looks at all assets on the balance sheets and expects banks to follow accounting rules.