hollys2042
Please try the below code in H7 and copied down.
=IF(DATEDIF(E7,F7,"y")>=20,25,IF(DATEDIF(E7,F7,"y")>=15,20,IF(DATEDIF(E7,F7,"y")>=10,17,IF(DATEDIF(E7,F7,"y")>=5,15,IF(DATEDIF(E7,F7,"y")>=1,10)))))&" Days"
Note:: for <1 year no logic is there, so for this the result will be "False...