I am retired Army and get a monthly pension; I also did some work cleaning pools and got paid on a 1099. My question is, do I need to file as self-employed and file social security and medicare taxes?

It depends;as a 1099 contractor, you need to file return aslongas the amount on Sch C line 29 / 31 is $400 or exceeds $400 also you must pay so called self employment tax aslongas the amount on Sch SE line 2 / 3 is $400 or exceeds $400; however, you can deduct up to 50% of your self employment tAX on 1040 line 27. If you are filing as a sole proprietor and/or a self-employed individual, you generally have to make estimated tax payments if you expect to owe tax of $1k or more when you file your return;however, dut to low penalties and interest, in my experience, many self employers do not pay quarterly estimated taxes to IRS/state UNLESS tax liabilities are large enough. You legally do not have to pay estimated tax for the current year if you had no tax liability for the prior year;y ou were a U.S. citizen or resident for the whole year; your prior tax year covered a 12 month period