the 50K is a collection in the year of sale. the pro-rata portion of this is taxable as capital gain. it is properly reported on line 21 not line 6
Line 21 (from instructions - interest would not be included)
Enter all money and the FMV of any property
or services you received during this tax year.
line 6 instructions
Line 6
Enter only mortgages, debts, or other
liabilities the buyer assumed from the seller or
took the property subject to. Don’t include
new mortgages the buyer gets from a bank,
the seller, or other sources
you stated the 50K was a down payment. that does not meet the criteria for items to enter on line 6
putting in on line 6 would result in you understating your income (capital gain) for the year of sale by about 77% of 50,000. if caught there would likely be substantial penalties and interest
