Click General ledger> Setup> Profit tax> Sales tax relations.

Press CTRL+N to create a new record.

In the Modulefield, select the module to which the sales tax is attached.

In the Type of taxfield, select the tax type that you want to attach with the sales tax.

In the Codefield, select the tax code.

In the Expense codefield, select the expense code.

In the Ledger accountfield, select an account for posting in the ledger.

Press CTRL+S or close the form.