MS Access - Date Field change to end of month

Hi Experts,

I have this query in Access:

INSERT INTO NOAH2_tblNAsAffiliations ( Contact1, Contact2, Affiliation, Address, Date1, Date2, Date5, Date6, Code1, Code2, Code5, Cntr3, Line1, Memo1, Memo2, AcctCo, Assn )
SELECT USER_dbo_certificates.CompanyID, v_inttblNAsContactsINDIVIDUAL.Contact, "3A" AS Expr1, v_inttblNAsContactsCOMPANY.KeyAddressID, USER_dbo_certificates.CreateDateTime, USER_dbo_certificates.ExpireDate, USER_dbo_certificates.IssueDate, USER_dbo_certificates.NextTPVMonthYear, "3A" AS Expr3, USER_dbo_certificates.Standard, USER_dbo_certificates.Status, USER_dbo_certificates.CertificateNo, "TBD" AS Expr4, USER_dbo_certificates.ModelDesignations, USER_dbo_certificates.Notes, "3A" AS Expr6, "3A" AS Expr7
FROM (USER_dbo_certificates INNER JOIN v_inttblNAsContactsCOMPANY ON USER_dbo_certificates.CompanyID = v_inttblNAsContactsCOMPANY.Contact) LEFT JOIN v_inttblNAsContactsINDIVIDUAL ON USER_dbo_certificates.AdminContactID = v_inttblNAsContactsINDIVIDUAL.UserID2;

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The Date field is:
[NextTPVMonthYear]

The date is currently:
NextTPVMonthYear
5/1/2016
3/1/2016
10/1/2017
10/1/2018
2/1/2017
9/1/2016
10/1/2017

I need the dates when Inserted into tblNAsAffiliations to be the last day of the month so like:
NextTPVMonthYear
4/30/2016
2/30/2016
9/30/2017
9/30/2018
1/30/2017
8/30/2016
9/30/2017

So something like:
(Date([NextTPVMonthYear], -1)

But I know this is not the correct syntax.

Please help and thanks