Your client will not pay SS tax, and no credit for SS wages for their retirement. Your client could put all their wages on schedule C and pay SS taxes thereby building their future SS benefits. Sorry its sometimes hard to get a direct answer on this forum

household help?

Earnings of $ 400 or more must be reported, and are subject to SE tax....even if it's $1 from four hundred different payers.

Line 7 vs Line 21 is driven by what your client received.

edit...and Line 7 vs Line 21 is old news (n/a for 2018...)

On Wages Worksheet, line 7, I detailed the the three people where client assisted as a household employee. If his wage is under $2100 per household, the payer is not required to file a W-2. Proseries enters this amount on Line 7 with the code HSH in front of it. I have used it since the Clinton presidency when the minimum HSH gradually increased from $50/quarter to the current $2100/yr. Is there any reason why I can't continue doing this as versus a Sch. C? Except that no social security tax is being paid?