Aggregates in SQL Server involving 3 tables

Question

Hello DBA's, I need some help. I have 3 tables namely: Credit Limit, Sold, Paid. What I need are the following:

1. I need to subtract the Paid from the Sold (we'll call this Unpaid)

2. I need to get the remaining Credit Limit by subtracting Credit Limit against Unpaid.

 

below is my query but it gives me a wrong result:

declare @CreditLimit table
(
    [AgentName] [nvarchar](50),
    [AgentID] [nvarchar](50),
    [CreditLimit] [decimal](18, 2)
)
INSERT into @CreditLimit
SELECT
    a.AgentName,
    a.AgentID,
    a.CreditLimit
FROM [dbo].[Agents] a


DECLARE @SoldInsurance table
(
    [AgentID] nvarchar(50),
    [TotalPremium] [decimal](18, 2)
)
insert into @SoldInsurance
SELECT m.AgentID, SUM(m.TotalPremium)
FROM tblMotorInsurance_eCI M
group by m.AgentID

declare @PaidInsurance table
(
    [AgentID] nvarchar(50),
    [ConvertedNetPremium] [decimal](18, 2),
    [ConvertedRegistryFee] [decimal](18, 2),
    [ConvertedVAT] [decimal](18, 2)
)
INSERT INTO @PaidInsurance
SELECT t.AgentID, sum(isnull(t.ConvertedNetPremium,0)), sum(isnull(t.[ConvertedRegistryFee],0)), sum(ISNULL(t.[ConvertedVAT],0)) AS PAYMENT
FROM TaxInvoiceDetails t
group by t.AgentID

SELECT  c.AgentName,
         C.AgentID,
        isnull(C.CreditLimit,0) as CreditLimit,
        isnull(m.TotalPremium,0) as InsuranceSold,
        isnull(T.ConvertedNetPremium,0) + isnull(t.ConvertedRegistryFee,0) + isnull(t.ConvertedVAT,0) as PaidInsurance,
        isnull(M.TotalPremium,0) - isnull(T.ConvertedNetPremium,0) - isnull(t.ConvertedRegistryFee,0) - isnull(t.ConvertedVAT,0) as UnpaidInsurance,
        ISNULL(c.CreditLimit,0) - isnull(M.TotalPremium,0) - isnull(T.ConvertedNetPremium,0) - isnull(t.ConvertedRegistryFee,0) - isnull(t.ConvertedVAT,0) as RemainingCreditLimit
FROM @CreditLimit c left outer join @SoldInsurance m on c.AgentID = m.AgentID
            left outer join @PaidInsurance t on m.AgentID = t.AgentID
where m.AgentID = '00003'
--where 1=1

I ran it and it gaves me this:

credit limit         sold             paid          unpaid     remaining credit limit
 50,000,000.00   58,232,073.40   32,487,325.40   25,744,748.00   (40,719,398.80)

 the paid and unpaid part is correct but on the Remaining Credit Limit is wrong. Please advice. Thank you.