The Securities and Exchange Commission will take up a staff proposal next week to ease the impact of falling oil prices on smaller oil companies by suspending rules that would force the companies to write down the value of their oil reserves.

The commission was to have voted on a different relief plan for the industry yesterday, but delayed action for a week to work on the new plan.

On another front, the SEC yesterday issued new guidance on the so-called "soft dollar" services that money managers receive from brokers. The costs of the services ultimately are charged to the money managers' customers.

The commission requires money managers to seek the lowest possible costs when making investments for their customers. Money managers can pay higher commissions, however, in return for legitimate services from the broker, such as market research.

The SEC yesterday broadened the kinds of services that qualify as exceptions to the low-cost rule, but specifically excluded airline tickets, hotel and some other expenses in connection with research seminars. Money managers would have to reimburse brokers in cash for these expenses rather than passing them on to customers.

The old standard provided that money managers could accept only those services that were not readily available to the general public on a commercial basis. The new standard permits brokers to provide "lawful and appropriate assistance" to money managers in the performance of investment responsibilities.

One effect of the change would be to permit money managers to receive computer-software services from brokers to aid in analyzing market trends or stock performance even though the software is "commercially available" to the public.

The accounting rules for oil reserves have become a crucial issue for hundreds of small and independent oil companies as they prepare to file first-quarter financial statements with the SEC.

"There is a concern whether that test makes sense in a volatile oil price environment," said Clarence Sampson, the SEC chief accountant.

Under current SEC rules, the companies are required to recalculate the value of their oil reserves in the first quarter of 1986 based on oil prices at the end of March. Because prices have fallen so sharply, the market value of oil and gas reserves has sunk far below book value. If the companies were required to take a write-off on the difference, some would be default on loan agreements with banks, the SEC staff said.

Initially, the SEC staff had favored a temporary change in its rules governing oil companies that use the "full-cost accounting method" -- primarily small and independent oil and gas firms.

The companies would have been permitted to ignore actual oil prices in calculating the value of their reserves in their quarterly reports to the SEC. Actual prices need not have been used until the companies prepared their year-end financial statements for 1986, and by that time, oil prices might well be higher, the SEC staff reasoned.

Apparently, second thoughts about the proposal on the part of the staff and the commission led to the delay.