Formula not calculating monthly "split" between range totals correctly

Attached file 151025 UTILISATION MIX.xlsx shows employees start on 30% utilisation. After three months, it increases to 50%. After six months some grades increase to 70%.

To establishes how many employees are on each "utilisation" level each month I tried the approach:

Range J2 - U2 (This does not work correctly):
=COUNTIF($B2:$B10,"<"&EOMONTH(J1,0))-COUNTIF($D2:$D10,"<"&EOMONTH(J1,0))-COUNTIFS($F$2:$F$10,"<>"&"",$F2:$F10,"<"&EOMONTH(J1,0))

Counts everyone in Col B employed in that month (because everyone HAS to be on at least 30%).
Deducts the number in Col D who are on 50% that month
Deducts the "non blank" cells in Col F who are on 70% that month.
Balance should be the number on 30%

Range J3 - U3 (Works correctly):
=COUNTIF($D2:$D10,"<"&EOMONTH(J1,0))-COUNTIFS($F$2:$F$10,"<>"&"",$F2:$F10,"<"&EOMONTH(J1,0))
Counts the number in Col D on 50% that month
Deducts the non-blanks in Col F on 70% that month.
Balance is those on 50%

Range J4 - U4 (Works correctly):
=COUNTIFS($F$2:$F$10,"<>"&"",$F2:$F10,"<"&EOMONTH(J1,0))
Counts the non-blanks in Col F on 70% that month.

Hope someone can see the "hole in the pole" and guide me?

Ochimus

How do you get 3 for August?

If understand the calculation:

30% =8
50% = 5
70% =1

therefore 30% = 8 -5 -1 = 2

Got it!!! Hence your approach.

Thanks to both for the prompt responses, and above all for FD'S brutally simple solution. Well deserved Reputation point.

(Reminds self to look up Occam's razor - AGAIN).

Ochimus