We either need more context, i.e. sentence before and after the term, or I am inclined to think that "L.F." followed by Número xxx is an error, and should be T.F. (Tribunal Fiscal), but how that fits with a marriage certificate, I don't know as you have not provided enough context:
síntesis de jurisprudencia del tribunal fiscal - AELEwww.aele.com › system › files › archivos › anatrib PDF
https://www.aele.com/system/files/archivos/anatrib/11.06 AT....Resolución del Tribunal Fiscal (TF) Nº 425-. 5-2011 relativa a la ... tributos ambientales en España en parti- ... damento 4; Exp. Nº 001-2009-PI, fun- damento 9 ...