You are able to pay upfront tax amounts throughout the year which will help to reduce a larger tax liability at the end of the year. You simply need to submit Form 1040-ES (NR) estimated tax payment amounts during the calendar year you are filing for. For instance, amounts submitted during 2023 will be applied to your 2023 tax return. If you end up paying too much, you will receive the excess as a refund. If you pay too little, any additional amounts owed will still be due by the filing deadline.