Read the 2003 rates in their historical context
This nine-page circular dated 31 March 2003 explains 15% gross withholding and the then 22% net-income election. Before the 2002 Budget the cited net rate was 24.5% for YA2002. These are historical rates and procedures. Today’s IRAS comparison states 15% gross or 24% net for non-resident professionals: https://www.iras.gov.sg/taxes/withholding-tax/payments-to-non-resident-professional-%28consultant-trainer-coach-etc-%29/non-resident-professional-vs-employee .
Who and what the original circular covers
A non-resident professional is an individual working under a contract for service in Singapore for less than 183 days in a calendar year. It also covers an overseas-based unincorporated firm of two or more partners, irrespective of individual partners’ residence. Gross income includes payer-borne costs: the original S$100,000 fee plus S$50,000 lodging/travel produces S$150,000 gross income.
Accommodation and airfare: gross is different from net
The older concession for airfare and accommodation for sixty days or less continues in the circular’s net-income election, but not under 15% gross withholding. Do not deduct those costs from the gross base merely because the payer paid suppliers directly. The distinction explains the later guest-lecture calculation.
The initial thirty-day election and upfront procedure
The first section describes a thirty-day irrevocable election from the payment/accrual date: the payer normally withholds 15% gross, then credits it against 22% net on election. Liability to pay can precede actual cash payment. An administrative upfront election, signed in IR37C section IV, permits withholding at 22% net instead of first paying gross withholding.
The April 2003 change and full date example
The circular then changes the election window to forty-five days from payment date when withholding became due on the following month’s fifteenth. For a S$100,000 amount due 30 April 2003, withhold S$15,000 by 15 May without upfront election. A revised IR37C through the payer between 16 May and 14 June can secure refund of any excess over 22% net; after 14 June the election is rejected. These dates are illustrations of the 2003 regime, not present filing instructions.
Multiple payments: the sixty-day limit
For the same professional/firm and engagement, consolidate payments whose first-to-last payment-date interval does not exceed sixty days. The old remittance date is the fifteenth of the month following the last eligible payment, and the net-income choice must be made upfront by that remittance date. Payments outside the sixty-day window are handled separately.
The guest-lecture example in full
Lectures run 1 April–15 May 2003. S$400 cash is paid 1 April, S$500 accommodation 17 May, and S$1,000 airfare 1 July. Gross withholding is 15% × S$900 = S$135 by 15 June, then S$150 on airfare by 15 August. Under upfront net election, the accommodation/airfare concession leaves 22% × S$400 = S$88 by 15 June and nil airfare withholding. July cannot be consolidated into April’s sixty-day window.
Annex A and the current deadline distinction
The flowchart has three routes: no net election means 15% gross; upfront election means 22% net under that edition; subsequent timely election means gross payment first and refund of the difference. Current withholding filing/payment is generally by the fifteenth of the SECOND month after payment, rather than the next-month dates above: https://www.iras.gov.sg/taxes/withholding-tax/withholding-tax-filing/withholding-tax-filing-and-payment-due-date/ . Use current procedures for an actual filing.
Official source
This article independently explains the substantive contents of the official PDF, including the relevant conditions, procedures and annexes. The linked document remains the authoritative source for its original wording, and later changes should be checked separately.
Read the official PDF ↗