Deductions & credits

Dear Mertz and Diane, 

Thankyou for this crucial clarification on form SE line 4c is the valve that go to SSA, I also checked on my previous years earning for SSA from the form SE  it matched with SE line 4c also some thing I learned that they use multiple of 10 to record your earning so they up or lower your earning to nearest multiple of 10. that  means for $ 1526 it will reduced to 1525 and for $ 1529 will go up 1530. strange? 

One more question still bugging me that when IRS do withhold tax from W2 with every pay check for current year 2025 then is there still need to pay estimated tax for 2025 in addition to W2.  Its look like once I earned my quarter with SSA I will not do any side work., so this will get rid of SE form fro me (one less headach) So do I still make estimated tax payment for 2025. I am an individule with just one full time job and my job doed not contribute to SSA  for this reason I did side job. Please help. Some good folks help me bhut this is still an issue with me. 

Thank you, 

Cassy007