I ended up learning a few things from all 3 answers so I thank you all very much.  I know this still needs some tweaking but here is what I ended up with: data _null_; call symput('to_delete',catt('saslib.ds_', put(intnx('month',today(),-25,'E'), yymmddn.))); run; proc delete data=&to_delete;   At some point I want to add in code so that the libname is a macro variable.  I'm thinking I should put some kind of "if exists" code in also.  And the idea of using the unique dataset to compare the datasets I want vs. the datasets I have is something I need to think about more.  Thanks so much. ... View more

I am, of course, assuming that your date_key variable contains valid SAS dates, which means it is numeric and has a YYMMDDN8. format attached.   With SAS dates, the code works, see here: data have; input date_key yymmdd10.; format date_key yymmdd10.; datalines; 2021-09-20 2021-08-31 ; proc sql noprint; select intnx('month',max(date_key),-12,'b') into : cutoff from have; quit; data _null_; cutoff = &cutoff; put cutoff yymmdd10.; run; Log excerpt: 82 data _null_; 83 cutoff = &cutoff; 84 put cutoff yymmdd10.; 85 run; 2020-09-01 ... View more