Date Parameters

See Code below -->> I need help with date parameters. I was told to pass in parameters for the meters date >>see underlined<<. I originally had specific years there but they do not want the years to be hard coded into the script. So I tried to replace with a parameter but need help. I have placed the years next to the parameters that were originally in the 'where' clause where the underline is.

SET NOCOUNT ON

DECLARE
@mtr_ageAdatetime, --<=1/1/94
@mtr_ageBdatetime, --<=1/1/07
@mtr_ageCdatetime; --<=1/1/07

set @mtr_ageA = (getdate()); (this should be a year not current date)
set @mtr_ageB =(getdate());
set @mtr_ageC =(getdate());



create table #aged_a
(
Entnovarchar (4),
Customer_Name varchar(100),
Loc_Nbrvarchar (10),
--Contract_Nbrvarchar (10),
Ref_Novarchar(20),
Meter_Novarchar(20),
Service_Areavarchar(10),
Pol_Subvarchar(10),
Kind_Codevarchar(10),
Mtr_Type varchar(10), --group a,b,c
Set_Datedatetime,
Mtr_Statusvarchar (1),
Meter_Locvarchar(20),
Addressvarchar(100),
Cityvarchar(30),
Statevarchar(2),
Zipvarchar(10)
)


Insert Into #aged_a
(Entno, Loc_Nbr, Meter_No, Service_Area, Pol_Sub, Kind_Code, Mtr_Type, Set_Date, Mtr_Status,
Meter_Loc, Address, City, State, Zip)

select
locn_entno,locn_locno, mplm_metno, locn_serv_area, locn_polsub_id, winv_subclass, winv_inv_type, mplm_set_date, mplm_meter_status,
ISNULL(mprl_rloc_desc,''), ISNULL(locn_addr, '') + ' ' + ISNULL(locn_addr2, ''), locn_city, locn_state,
locn_postal
FROM rs3_prod.dbo.MP_Location_Meter (NOLOCK)
INNER JOIN rs3_prod.dbo.WO_Inventory (NOLOCK)
ON mplm_entno = winv_entno
and mplm_metno = winv_invno
INNER JOIN rs3_prod.dbo.RS_Location (NOLOCK)
ON winv_entno = locn_entno
and winv_locno = locn_locno
Left outer join rs3_prod.dbo.MP_Read_Location (NOLOCK)
on mprl_rloc_code = mplm_rloc_code
WHERE (winv_inv_type = 'GROUP A' and mplm_set_date <=@mtr_ageA )
or (winv_inv_type = 'Group B'and mplm_set_date <=@mtr_ageB )
or (winv_inv_type ='Group C' and mplm_set_date <=@mtr_ageC )