Let and Lambda

[georgiboy]

Not sure you can refer to a column in a table you have defined like 'tx[Date]'

If you define the table, in my mind it becomes more of a range to the LET formula, as such you can refer to the columns with Index:

=LET(tx, tblTransactions,
          method, "Transfer",
          tx_date, TODAY(),
          res, FILTER(INDEX(tx,,1), (INDEX(tx,,2)=method)*(INDEX(tx,,1)>=tx_date)),
          res)

Other than that you would use the table name itself:

=LET(method, "Transfer",
          tx_date, TODAY(),
          res, FILTER(tblTransactions[Date], (tblTransactions[Method]=method)*(tblTransactions[Date]>=tx_date)),
          res)

If you renamed the table 'tx' then 'tx[Date]' would be fine.