The Department of Commerce sums the payments (made to resources) to arrive at GDP in the form of compensation of employees, rents, profits, net interest, indirect taxes and depreciation.
I bracketed made to resources as I think it is a participle phrase and functions as a adjective (according to this site : http://www.chompchomp.com/terms/participlephrase.htm),
therefore can be ignored when understanding the function of to in the context.
And the to here doesn't seem to tell the purpose of sums the payments, so the only interpretation I can come up with is :
The Department of Commerce sums the payments, and the payments arrive at GDP in the form of compensation of employees, rents, profits, net interest, indirect taxes and depreciation.
So the to in the original context probably acts as an object complement, the object being payments and to arrive at.. being the complement. (according to this site: https://www.thefreedictionary.com/Object-Complements.htm)
Is my understanding of the meaning of the context and the function of to correct?