Need Formula or command for if billed to date equals zero then use retention.

I am not very good at Excel but I have a big problem. I own a construction company in AZ and my bookeeper who is supposed to be a pro @ Excel keeps messing up the billings forcing me to get my billings rejected and sometimes waiting another 30 days to be able to bill. It is killing me. I see that she types over formulas and then copy and paste's the sheets to be used later which do not add up correctly due to overwriting the previous formulas. I believe I fixed our AIA Billing sheet the only thing I am having problems with is the following. I want a formula that automatically add in the 10% retention the contractors withhold from us till the job is complete. She usually types it in and half the time she gets it wrong. My billing sheet is designed to do take the contract value add any change orders give you a new contract price you type in how much you have completed it then subtracts the retention gives you the total then it subtract the previous billed amounts and that's what you have coming. All this works on my sheet however I would like a formula so that if everything minus retention has been billed it automatically bills retention. Please see the following. Thank you.

Description of Work:

D18 Original Contract Amount $125,198.00 Manually entered

D20 Change Order Total $9,206.10 Manually entered

Through C/O #: 3 Manually entered

D22 Total Revised Contract $134,404.10 =D18 + D20

D24 Value of Work Performed to Date $134,404.10 Manually entered

D26 Value of Materials Stored On Site $0.00 Manually entered

D28 Value of Materials Stored Off Site $0.00 Manually entered

D30 Current Month (Stored Materials) $0.00 =D26+D28

D32 Total $134,404.10 =D24+D30

D34 Less _10___% Retainage $13,440.41 =D32*10% (=10% of D32)

D36 Amount Earned to Date $120,963.69 =D32-D34

D38 Less Previous Billings/Payments $120,963.69 Manually entered

D40 Less Adjustments/Joint Checks $0.00 Manually entered

D42 Less Pending Back Charges $0.00 Manually entered

D44 Total Amount this Requisition $0.00 =D36-D38 which is perfect but is there a formula I could enter that would tell it to bill retention for instance if D36-D38 = 0 then bill the retention D34??? Thank you.

Deleted, OP complied with request.

SK Is right change the title and a sample sheet would be good (remove sensitive data 1st or make up a dummy job file). If you do provide a sample I could hopefully identify any other problem areas as well.

Having said that and because I am bored waiting for the wife to get ready :-( ,
I am providing a sample of what COULD be achieved by using 'Data validation or the better 'Sheet Protection.
Check both tabs in the sample to see what I mean.

Book1.xlsm

Hello Laz & Welcome to the Forum,

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