Upon the payment of contributions into the unemployment fund of a State which are required under the unemployment compensation law of that State with respect to remuneration on the basis of which, prior to such payment into the proper fund, the taxpayer erroneously paid an amount as contributions under another unemployment compensation law, the payment into the proper fund shall, for purposes of credit against the tax, be deemed to have been made at the time of the erroneous payment. If, by reason of such other law, the taxpayer was entitled to cease paying contributions with respect to services subject to such other law, the payment into the proper fund shall, for purposes of credit against the tax, be deemed to have been made on the date the return for the taxable year was filed under section 6071.