you don't say what your *tables* structure is; you should have, at minimum,
two tables, as
tblClients
ClientID (primary key)
<other fields that describe a client, but NOTHING about payments>
tblPayments
PaymentID (primary key)
ClientID (foreign key from tblClients)
PaymentDate
<other fields that describe a single payment from a single client, but
NOTHING about the client other than the ClientID>
that's a standard one-to-many relationship: one client may make many
payments, but each payment is made by only one client.
a standard form setup would be a main form bound to tblClients, with a
subform bound to tblPayments; the mainform/subform linked on the ClientID
field in each table.
hth