Do I Need DatePart Or Similar

I have a function that uses the following statement in it

SELECT src_terrier.Areacode, src_terrier.siteref, src_terrier.estatename, src_terrier.Securitised, src_terrier.unitref, src_terrier.unittype,
src_terrier.unittype_count, src_terrier.tenantname, src_terrier.tenantstatus, src_terrier.tenantstatus_count, src_terrier.unitstatus,
src_terrier.unitstatus_count, src_terrier.floortotal, src_terrier.floortotocc, src_terrier.initialvacarea, src_terrier.initialvacnet, src_terrier.TotalRent,
src_terrier.NetRent, src_terrier.FinalRtLsincSC, src_terrier.ErvTot, src_terrier.tenancyterm, src_terrier.landact, src_terrier.datadate,
src_div_mgr.div_mgr, src_portfolio_mgr.portfolio_mgr, src_centre_list.propcat, src_tbl_rental.budgeted_net_rent,
src_tbl_rental.budgeted_occupancy
FROM src_terrier INNER JOIN
src_centre_list ON src_terrier.siteref = src_centre_list.Site_Ref AND src_terrier.Areacode = src_centre_list.Division INNER JOIN
src_div_mgr ON src_centre_list.Division = src_div_mgr.division INNER JOIN
src_portfolio_mgr ON src_centre_list.Portfolio_no = src_portfolio_mgr.portfolio_no LEFT OUTER JOIN
src_tbl_rental ON src_terrier.siteref = src_tbl_rental.site_ref

WHERE (src_terrier.datadate = @dt_src_date) AND
(src_terrier.Areacode = @chr_div) AND
(src_centre_list.Portfolio_no = @vch_portfolio_no) AND
(src_centre_list.propcat = @vch_prop_cat) AND
(src_tbl_rental.site_ref = src_terrier.siteref)

The problem I have is that the 'src_terrier.datadate' is passed through as mm/dd/yyyy (which I do actually want to change to dd/mm/yyyy as that is how the data is stored) however, the src_date within the table src_tbl_rental is only set to 01/mm/yyyy. When I put an inner join on the date element it obviously does not find it as the sample data I am using is as follows

src_terrier = 28/04/2006 and src_tbl_rental is 01/04/2006. Therefore if I pass the same parameter value through the dates are not the same and I get no data at all.

How can I specify that for the purposes of the src_tbl_rental element of the select query, that I only want it to match the mm/yyyy part of the src_date.

Therefore if some passes in
28/04.2006 it will get the records from the terrier table that match that date, and only the records from rental that match the 04/2006 part of the date.

Anybody confused by that , cause I am!

Regards