Is it necessary to file a tax return if no tax is owed and no refund due? My only income is social security and pension benefits. I am 76 years old.

That might depend on the amount of the pension benefits you are receiving.  Your age is not relevant.

You need to file a federal return if half your Social Security plus your other income is $25,000 when filing single or head of household, or $32,000 when filing married filing jointly, $0 if you are filing married filing separately.

Who has to file?

http://www.irs.gov/uac/Do-I-Need-to-File-a-Tax-Return%3F

It depends. If the amount of your pension income is above the filing requirement threshold for your filing status and age, you would still need to file. Also, depending on the amount of your pension, it could cause part of your Social Security benefits to be taxable.

If you didn't receive any income subject to taxation in the year 2022, then you aren't required to file a Federal tax return for 2022 unless you need to report another tax item.

If you made any estimated tax payments for 2022, then you should file a return to claim a refund of the estimated taxes paid.

Please see this article from TurboTax for more information regarding who is required to file a tax return.

Click here for information from the IRS regarding who should file and who needs to file.