I'm 77 years old, rec'd $30K from Social Security plus $9370 in Regular IRA and Emergency Services Retirement RMD, plus $0 net income on W2-Gs. Must I file a return?

Yes, RMD's are taxable.

No, a W2-G does not automatically make a return required for you.

However, if your income is above the standard deduction, then a return is required and your social security can be taxable. Depending on your other income up to 85% of your Social Security can be taxable.   So if you have $11,000 in RMD's plus 1/2 of your social security benefits of $30,000, you would have $26,000 in income subject to taxation which would be above your standard deduction for a person over 65 of $16,550. Also, depending on your basis in your IRA some or all of that may be taxable.  

So the best thing to do in your situation with multiple sources of income would be to enter it all into TurboTax and then go from there as it sounds like a good possibility that you would need to file a return.  If the amount on line 11 on your form 1040 is higher than the amount on line 12 or if you a tax liability on line 16, then you definitely need to file. 

If you fall into the following, 85% of your social security is taxable income

• Single with income above $34,000
• Married Filing Jointly with income above $44,000
• Married Filing Separate regardless of income

If you fall into the following, 50% of your social security is taxable income

• Single with combined income between $25,000-$34,000
• Married Filing Jointly with combined income between $32,000 and $44,000

Your combined income is calculated by adding your

• AGI plus
• Nontaxable Interest plus
• 1/2 of your social security Benefits

Social Security Benefits Taxes