The amount you are referring to is not filled in by you or your accountant. This number is ***** by the IRS Form Schedule SE itself.
According to its explanation, this number $118,500 is the highest number for any taxpayer to pay social security tax on his/her tax return. If a taxpayer has a W-2 wage income plus self employment income more than 118,500, the taxpayer is required to pay social security tax only on 118,500.
Therefore, this number did not apply to you. The calculation of your SE schedule did not concern or use this number.
As you described above, your self employment tax is calculated in Section A using the number you described.
Therefore, if you are reviewing your tax return, you can ignore this number of 118,500 and this section B. They do not seem to have been used to calculate your self employment tax.
If you continue to read the form of Schedule SE, on page 2, there is a number of 4,880 on line 14. That is a pre-provided number as well by the form by the IRS. The purpose for the IRS to provide these numbers is to help the taxpayer to correctly fill out the tax return.
Fiona Chen, MPA, Ph.D., CPA, ABV, CFF, CITP