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US vs Singapore

How the United States and Singapore compare on adviser fees, the people who prepare research and development claims, and the checks on those claims, set out side by side with official sources.

On this page
  1. Where they differ
  2. Where they are similar
  3. Sources

This page sets the federal research credit in the United States beside the R&D tax deductions and Enterprise Innovation Scheme in Singapore. It compares how advisers may be paid, how preparers are registered and identified, and the checks, penalties and appeal routes that apply to claims. Each country page gives the fuller rules and sources.

This table simplifies each country's rules for comparison. See the country pages for detail and sources. Last reviewed pending.

Topic United States Singapore
Tax authority Internal Revenue Service (IRS), part of the Treasury Department1Source 1Internal Revenue Service, Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021), page 1 footer ("Department of the Treasury Internal Revenue Service"). https://www.irs.gov/pub/irs-pdf/p5.pdf (accessed 11 October 2026). Inland Revenue Authority of Singapore (IRAS)2Source 2Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 14C(1) and 14D(1), (1A) and (11). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr14D- (accessed 11 October 2026).
Scheme Credit for increasing research activities under Section 41, claimed on Form 67653Source 3Office of the Law Revision Counsel, 26 U.S.C. 41, Credit for increasing research activities, subsections (a) and (c)(4)(A), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleA-chap1-subchapA-partIV-subpartD-sec41.htm (accessed 11 October 2026).4Source 4Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026). R&D deductions under sections 14C and 14D of the Income Tax Act 1947, enhanced by the Enterprise Innovation Scheme (EIS) for YA 2024 to YA 20282Source 2Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 14C(1) and 14D(1), (1A) and (11). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr14D- (accessed 11 October 2026).5Source 5Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Enterprise Innovation Scheme (Third Edition, published 31 August 2026), paragraphs 2.1, 4.1 to 4.5 and 5.8, and Annex A, paragraphs 1.1 to 1.3 and 2.1. https://www.iras.gov.sg/docs/default-source/e-tax/etaxguide_cit_enterprise-innovation-scheme.pdf?sfvrsn=3a36afd3_12 (accessed 11 October 2026).
Rules on adviser fees Circular 230 generally bars contingent fees for practitioners, with exceptions6Source 6Treasury Department, Circular No. 230, 31 CFR 10.27, Fees, paragraphs (b)(1) to (b)(4) and (c)(1) to (c)(2), with source note T.D. 9359 (eCFR text up to date as of 8 October 2026). https://www.ecfr.gov/current/title-31/subtitle-A/part-10/subpart-B/section-10.27 (accessed 11 October 2026).; a 2014 court decision limited it for refund claims filed before an audit7Source 7US District Court for the District of Columbia, Ridgely v. Lew, Civil Action No. 1:12-cv-00565 (CRC), Memorandum Opinion, 16 July 2014, pages 1 and 14 to 15. https://www.govinfo.gov/content/pkg/USCOURTS-dcd-1_12-cv-00565/pdf/USCOURTS-dcd-1_12-cv-00565-1.pdf (accessed 11 October 2026).; a 2024 proposal to replace it was not final8Source 8Treasury Department and Internal Revenue Service, Regulations Governing Practice Before the Internal Revenue Service, notice of proposed rulemaking, 89 FR 104915 (26 December 2024), Dates, Explanation of Provisions part B and proposed section 10.51(b). https://www.federalregister.gov/documents/2024/12/26/2024-29371/regulations-governing-practice-before-the-internal-revenue-service (accessed 11 October 2026). No statutory cap or ban identified; offence to willfully assist another to obtain an EIS cash payout they are not entitled to9Source 9Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 37R(1), (3) and (34) and 37S(1) to (4). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr37S- (accessed 11 October 2026).
Professional body rules AICPA members in public practice may not prepare an original or amended return or refund claim for a contingent fee10Source 10American Institute of CPAs, Code of Professional Conduct (updated for all official releases through September 2026), ET 1.510.001, paragraphs .01b, .03 and .04, and ET 1.510.010, paragraphs .03 to .05. https://pub.aicpa.org/codeofconduct/ethicsresources/et-cod.pdf (accessed 11 October 2026). ISCA Code treats contingent fees as a possible self-interest threat and bans them for audits11Source 11Institute of Singapore Chartered Accountants, Ethics Pronouncement 100: Code of Professional Conduct and Ethics (effective 1 July 2025), paragraphs SG010.1, 330.4 A1 and R410.9. https://isca.org.sg/docs/default-source/ep-100/eps-100/code-of-ethics-for-isca-ep-100-(effective-1-jul-25).pdf (accessed 11 October 2026).; SCTP Code does not use the term12Source 12Singapore Chartered Tax Professionals, Code of Ethics and Professional Conduct (effective 1 September 2026), paragraphs 2.2, 3.10 and 8.18. https://www.sctp.org.sg/Ethics-Code.pdf (accessed 11 October 2026).
Adviser registration Paid preparers need a preparer tax identification number (PTIN); no examination is required13Source 13Internal Revenue Service, PTIN requirements for tax return preparers (page last reviewed or updated 16 October 2025). https://www.irs.gov/tax-professionals/ptin-requirements-for-tax-return-preparers (accessed 11 October 2026).14Source 14Internal Revenue Service, Understanding tax return preparer credentials and qualifications, sections "Unlimited representation rights", "Limited representation rights", "Annual filing season program participants" and "PTIN holders" (page last reviewed or updated 29 January 2026). https://www.irs.gov/tax-professionals/understanding-tax-return-preparer-credentials-and-qualifications (accessed 11 October 2026). No statutory registration identified; voluntary accreditation through SCTP15Source 15Inland Revenue Authority of Singapore, Enhanced IRAS-tax agent Relationship Framework (last updated 28 January 2026), section "Accreditation for tax professionals". https://www.iras.gov.sg/quick-links/tax-agents/iras-tax-agent-relationship (accessed 11 October 2026).
Preparer identification The signing preparer's PTIN, and the firm's number where relevant, go on the return or refund claim16Source 16Treasury Department and Internal Revenue Service, 26 CFR 1.6109-2, Tax return preparers furnishing identifying numbers for returns or claims for refund and related requirements, paragraphs (a)(1) to (a)(3). https://www.ecfr.gov/current/title-26/section-1.6109-2 (accessed 11 October 2026).; Form 6765 has no preparer field17Source 17Internal Revenue Service, Form 6765, Credit for Increasing Research Activities (Rev. December 2024), pages 1 to 4. https://www.irs.gov/pub/irs-pdf/f6765.pdf (accessed 11 October 2026). Form C-S asks for the person who reviewed the return18Source 18Inland Revenue Authority of Singapore, Explanatory Notes to Form C-S for Year of Assessment (YA) 2026, section "Particulars of Person who Reviewed the Return". https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/explanatory-notes-to-ya-2026-form-c-s.pdf?sfvrsn=1d2386c1_20 (accessed 11 October 2026).; the R&D Claim Form asks for a technical contact, not the adviser or fee19Source 19Inland Revenue Authority of Singapore, Research and Development (R&D) Claim Form (YA 2019 and onwards), Part 1 (note 1), Part 4 "Declaration" and Part 5, item 5O. https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/rnd-claim-form-(ya-2019-n-after).pdf?sfvrsn=72929970_40 (accessed 11 October 2026).
Claim integrity measures No advance notice4Source 4Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026).; refund claims must list business components, research activities and expense totals20Source 20Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 4, 7 and 21 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026).; Section G business component detail required for tax years beginning after 2025, with exceptions4Source 4Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026). No advance notification or approval; self-assessment; R&D Claim Form filed with Form C or kept for IRAS21Source 21Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Research and Development Tax Measures (Eighth Edition, published 30 January 2026), paragraphs 2.2, 11.1 (with footnote 21), 13.1 to 13.5 (with footnote 23). https://www.iras.gov.sg/docs/default-source/e-tax/research-and-development-tax-measures-etax-guide_6th-edition.pdf?sfvrsn=1f38a2e8_27 (accessed 11 October 2026).; separate cash payout application22Source 22Inland Revenue Authority of Singapore, Enterprise Innovation Scheme (EIS) (last updated 23 September 2026), sections "Option to Convert Qualifying Expenditure into a Cash Payout" and "How & When to Claim the EIS Benefits". https://www.iras.gov.sg/schemes/disbursement-schemes/enterprise-innovation-scheme-(eis) (accessed 11 October 2026).
Penalties 20 percent accuracy-related penalty23Source 23Office of the Law Revision Counsel, 26 U.S.C. 6662, Imposition of accuracy-related penalty on underpayments, subsections (a), (b), (c) and (d)(1), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleF-chap68-subchapA-partII-sec6662.htm (accessed 11 October 2026).; 20 percent of an excessive refund claim24Source 24Office of the Law Revision Counsel, 26 U.S.C. 6676, Erroneous claim for refund or credit, subsections (a) and (b), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleF-chap68-subchapB-partI-sec6676.htm (accessed 11 October 2026).; preparer penalty of the greater of $1,000 or 50 percent of income derived25Source 25Office of the Law Revision Counsel, 26 U.S.C. 6694, Understatement of taxpayer's liability by tax return preparer, subsection (a)(1), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleF-chap68-subchapB-partI-sec6694.htm (accessed 11 October 2026). Double the tax undercharged for an incorrect return made without reasonable excuse or through negligence; four times for willful evasion26Source 26Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 95(2) and 96A(1). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr95- (accessed 11 October 2026).; parallel cash payout penalties9Source 9Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 37R(1), (3) and (34) and 37S(1) to (4). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr37S- (accessed 11 October 2026).
Reviews and disputes IRS checks each research credit refund claim for validity27Source 27Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 3 to 7 and 16 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026).; Independent Office of Appeals, then the Tax Court or a refund suit28Source 28Internal Revenue Service, Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021), pages 1 to 6. https://www.irs.gov/pub/irs-pdf/p5.pdf (accessed 11 October 2026).; claims rejected as deficient cannot go to Appeals29Source 29Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 7 and 15 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026). IRAS reviews claim form information and may consult IPOS International and its Technical Advisory Panel21Source 21Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Research and Development Tax Measures (Eighth Edition, published 30 January 2026), paragraphs 2.2, 11.1 (with footnote 21), 13.1 to 13.5 (with footnote 23). https://www.iras.gov.sg/docs/default-source/e-tax/research-and-development-tax-measures-etax-guide_6th-edition.pdf?sfvrsn=1f38a2e8_27 (accessed 11 October 2026).; objection within two months, then the Income Tax Board of Review30Source 30Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Corporate Income Tax: Objection and Appeal Process (Fourth Edition, published 30 January 2026), paragraphs 2.1, 3.3, 6.1 and 6.2. https://www.iras.gov.sg/media/docs/default-source/e-tax/e-tax-guide_cit_objection-and-appeal-process.pdf?sfvrsn=83675467_11 (accessed 11 October 2026).

Where they differ

Form of relief. The US research credit is a credit against tax.3Source 3Office of the Law Revision Counsel, 26 U.S.C. 41, Credit for increasing research activities, subsections (a) and (c)(4)(A), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleA-chap1-subchapA-partIV-subpartD-sec41.htm (accessed 11 October 2026). Singapore gives deductions for R&D expenditure, and under the Enterprise Innovation Scheme an eligible business may convert part of its qualifying expenditure into a cash payout instead.2Source 2Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 14C(1) and 14D(1), (1A) and (11). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr14D- (accessed 11 October 2026).5Source 5Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Enterprise Innovation Scheme (Third Edition, published 31 August 2026), paragraphs 2.1, 4.1 to 4.5 and 5.8, and Annex A, paragraphs 1.1 to 1.3 and 2.1. https://www.iras.gov.sg/docs/default-source/e-tax/etaxguide_cit_enterprise-innovation-scheme.pdf?sfvrsn=3a36afd3_12 (accessed 11 October 2026).

Fees. The United States restricts contingent fees for practitioners through section 10.27 of Circular 230, limited by a 2014 court decision for refund claims filed before an audit.6Source 6Treasury Department, Circular No. 230, 31 CFR 10.27, Fees, paragraphs (b)(1) to (b)(4) and (c)(1) to (c)(2), with source note T.D. 9359 (eCFR text up to date as of 8 October 2026). https://www.ecfr.gov/current/title-31/subtitle-A/part-10/subpart-B/section-10.27 (accessed 11 October 2026).7Source 7US District Court for the District of Columbia, Ridgely v. Lew, Civil Action No. 1:12-cv-00565 (CRC), Memorandum Opinion, 16 July 2014, pages 1 and 14 to 15. https://www.govinfo.gov/content/pkg/USCOURTS-dcd-1_12-cv-00565/pdf/USCOURTS-dcd-1_12-cv-00565-1.pdf (accessed 11 October 2026). No provision of Singapore's Income Tax Act 1947 that caps, prohibits or requires disclosure of contingent fees was identified. The Act does make it an offence to willfully assist another person to obtain a cash payout that person is not entitled to.9Source 9Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 37R(1), (3) and (34) and 37S(1) to (4). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr37S- (accessed 11 October 2026). See Contingent fee rules by country.

Professional bodies. The AICPA Code bars its members in public practice from preparing returns or refund claims for a contingent fee.10Source 10American Institute of CPAs, Code of Professional Conduct (updated for all official releases through September 2026), ET 1.510.001, paragraphs .01b, .03 and .04, and ET 1.510.010, paragraphs .03 to .05. https://pub.aicpa.org/codeofconduct/ethicsresources/et-cod.pdf (accessed 11 October 2026). The ISCA Code prohibits contingent fees for audit engagements and treats them as a possible self-interest threat, and the SCTP Code does not use the term.11Source 11Institute of Singapore Chartered Accountants, Ethics Pronouncement 100: Code of Professional Conduct and Ethics (effective 1 July 2025), paragraphs SG010.1, 330.4 A1 and R410.9. https://isca.org.sg/docs/default-source/ep-100/eps-100/code-of-ethics-for-isca-ep-100-(effective-1-jul-25).pdf (accessed 11 October 2026).12Source 12Singapore Chartered Tax Professionals, Code of Ethics and Professional Conduct (effective 1 September 2026), paragraphs 2.2, 3.10 and 8.18. https://www.sctp.org.sg/Ethics-Code.pdf (accessed 11 October 2026).

Registration. A paid US preparer must have a PTIN.13Source 13Internal Revenue Service, PTIN requirements for tax return preparers (page last reviewed or updated 16 October 2025). https://www.irs.gov/tax-professionals/ptin-requirements-for-tax-return-preparers (accessed 11 October 2026). No statutory registration or licensing scheme for paid tax advisers was identified for Singapore, where accreditation through SCTP is something tax professionals may apply for.15Source 15Inland Revenue Authority of Singapore, Enhanced IRAS-tax agent Relationship Framework (last updated 28 January 2026), section "Accreditation for tax professionals". https://www.iras.gov.sg/quick-links/tax-agents/iras-tax-agent-relationship (accessed 11 October 2026). See Adviser registration by country.

Identification. The US return carries the signing preparer's PTIN.16Source 16Treasury Department and Internal Revenue Service, 26 CFR 1.6109-2, Tax return preparers furnishing identifying numbers for returns or claims for refund and related requirements, paragraphs (a)(1) to (a)(3). https://www.ecfr.gov/current/title-26/section-1.6109-2 (accessed 11 October 2026). Singapore's Form C-S asks for the particulars of the person who reviewed the return, including an SCTP membership number where that person is accredited.18Source 18Inland Revenue Authority of Singapore, Explanatory Notes to Form C-S for Year of Assessment (YA) 2026, section "Particulars of Person who Reviewed the Return". https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/explanatory-notes-to-ya-2026-form-c-s.pdf?sfvrsn=1d2386c1_20 (accessed 11 October 2026).

Where they are similar

Neither country requires advance notice before a claim. The IRS receives the required information with the return or refund claim, and IRAS states that a taxpayer need not apply to any government agency and must self-assess whether its activities qualify.4Source 4Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026).21Source 21Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Research and Development Tax Measures (Eighth Edition, published 30 January 2026), paragraphs 2.2, 11.1 (with footnote 21), 13.1 to 13.5 (with footnote 23). https://www.iras.gov.sg/docs/default-source/e-tax/research-and-development-tax-measures-etax-guide_6th-edition.pdf?sfvrsn=1f38a2e8_27 (accessed 11 October 2026). See Claim integrity measures by country.

Neither research claim form asks how an adviser was paid. Form 6765 and its instructions do not ask who prepared the calculation or how that person was paid, and Singapore's R&D Claim Form does not ask who prepared the claim or how that person is paid.4Source 4Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026).20Source 20Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 4, 7 and 21 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026).19Source 19Inland Revenue Authority of Singapore, Research and Development (R&D) Claim Form (YA 2019 and onwards), Part 1 (note 1), Part 4 "Declaration" and Part 5, item 5O. https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/rnd-claim-form-(ya-2019-n-after).pdf?sfvrsn=72929970_40 (accessed 11 October 2026).

Both set penalties on the business by reference to the tax at stake: 20 percent of the relevant underpayment in the United States, and double the tax undercharged, or four times for willful evasion, in Singapore.23Source 23Office of the Law Revision Counsel, 26 U.S.C. 6662, Imposition of accuracy-related penalty on underpayments, subsections (a), (b), (c) and (d)(1), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleF-chap68-subchapA-partII-sec6662.htm (accessed 11 October 2026).26Source 26Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 95(2) and 96A(1). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr95- (accessed 11 October 2026). See Penalties by country.

Both provide a route to the courts: through the IRS Independent Office of Appeals and then the courts in the United States, and through an objection, the Income Tax Board of Review and, on a question of law, the High Court in Singapore.28Source 28Internal Revenue Service, Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021), pages 1 to 6. https://www.irs.gov/pub/irs-pdf/p5.pdf (accessed 11 October 2026).30Source 30Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Corporate Income Tax: Objection and Appeal Process (Fourth Edition, published 30 January 2026), paragraphs 2.1, 3.3, 6.1 and 6.2. https://www.iras.gov.sg/media/docs/default-source/e-tax/e-tax-guide_cit_objection-and-appeal-process.pdf?sfvrsn=83675467_11 (accessed 11 October 2026).

Sources

  1. Internal Revenue Service, Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021), page 1 footer ("Department of the Treasury Internal Revenue Service"). https://www.irs.gov/pub/irs-pdf/p5.pdf (accessed 11 October 2026).  Back
  2. Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 14C(1) and 14D(1), (1A) and (11). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr14D- (accessed 11 October 2026).    Back
  3. Office of the Law Revision Counsel, 26 U.S.C. 41, Credit for increasing research activities, subsections (a) and (c)(4)(A), United States Code 2024 edition published by the Government Publishing Office. https://www.govinfo.gov/content/pkg/USCODE-2024-title26/html/USCODE-2024-title26-subtitleA-chap1-subchapA-partIV-subpartD-sec41.htm (accessed 11 October 2026).   Back
  4. Internal Revenue Service, Instructions for Form 6765 (Rev. December 2025), What's New, Purpose of Form, "Requirements To Complete Section G" and "Research Credit Claims on Amended Returns". https://www.irs.gov/instructions/i6765 (accessed 11 October 2026).      Back
  5. Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Enterprise Innovation Scheme (Third Edition, published 31 August 2026), paragraphs 2.1, 4.1 to 4.5 and 5.8, and Annex A, paragraphs 1.1 to 1.3 and 2.1. https://www.iras.gov.sg/docs/default-source/e-tax/etaxguide_cit_enterprise-innovation-scheme.pdf?sfvrsn=3a36afd3_12 (accessed 11 October 2026).   Back
  6. Treasury Department, Circular No. 230, 31 CFR 10.27, Fees, paragraphs (b)(1) to (b)(4) and (c)(1) to (c)(2), with source note T.D. 9359 (eCFR text up to date as of 8 October 2026). https://www.ecfr.gov/current/title-31/subtitle-A/part-10/subpart-B/section-10.27 (accessed 11 October 2026).   Back
  7. US District Court for the District of Columbia, Ridgely v. Lew, Civil Action No. 1:12-cv-00565 (CRC), Memorandum Opinion, 16 July 2014, pages 1 and 14 to 15. https://www.govinfo.gov/content/pkg/USCOURTS-dcd-1_12-cv-00565/pdf/USCOURTS-dcd-1_12-cv-00565-1.pdf (accessed 11 October 2026).   Back
  8. Treasury Department and Internal Revenue Service, Regulations Governing Practice Before the Internal Revenue Service, notice of proposed rulemaking, 89 FR 104915 (26 December 2024), Dates, Explanation of Provisions part B and proposed section 10.51(b). https://www.federalregister.gov/documents/2024/12/26/2024-29371/regulations-governing-practice-before-the-internal-revenue-service (accessed 11 October 2026).  Back
  9. Attorney-General's Chambers, Income Tax Act 1947 (Singapore Statutes Online, current version), sections 37R(1), (3) and (34) and 37S(1) to (4). https://sso.agc.gov.sg/Act/ITA1947?ProvIds=pr37S- (accessed 11 October 2026).    Back
  10. American Institute of CPAs, Code of Professional Conduct (updated for all official releases through September 2026), ET 1.510.001, paragraphs .01b, .03 and .04, and ET 1.510.010, paragraphs .03 to .05. https://pub.aicpa.org/codeofconduct/ethicsresources/et-cod.pdf (accessed 11 October 2026).   Back
  11. Institute of Singapore Chartered Accountants, Ethics Pronouncement 100: Code of Professional Conduct and Ethics (effective 1 July 2025), paragraphs SG010.1, 330.4 A1 and R410.9. https://isca.org.sg/docs/default-source/ep-100/eps-100/code-of-ethics-for-isca-ep-100-(effective-1-jul-25).pdf (accessed 11 October 2026).   Back
  12. Singapore Chartered Tax Professionals, Code of Ethics and Professional Conduct (effective 1 September 2026), paragraphs 2.2, 3.10 and 8.18. https://www.sctp.org.sg/Ethics-Code.pdf (accessed 11 October 2026).   Back
  13. Internal Revenue Service, PTIN requirements for tax return preparers (page last reviewed or updated 16 October 2025). https://www.irs.gov/tax-professionals/ptin-requirements-for-tax-return-preparers (accessed 11 October 2026).   Back
  14. Internal Revenue Service, Understanding tax return preparer credentials and qualifications, sections "Unlimited representation rights", "Limited representation rights", "Annual filing season program participants" and "PTIN holders" (page last reviewed or updated 29 January 2026). https://www.irs.gov/tax-professionals/understanding-tax-return-preparer-credentials-and-qualifications (accessed 11 October 2026).  Back
  15. Inland Revenue Authority of Singapore, Enhanced IRAS-tax agent Relationship Framework (last updated 28 January 2026), section "Accreditation for tax professionals". https://www.iras.gov.sg/quick-links/tax-agents/iras-tax-agent-relationship (accessed 11 October 2026).   Back
  16. Treasury Department and Internal Revenue Service, 26 CFR 1.6109-2, Tax return preparers furnishing identifying numbers for returns or claims for refund and related requirements, paragraphs (a)(1) to (a)(3). https://www.ecfr.gov/current/title-26/section-1.6109-2 (accessed 11 October 2026).   Back
  17. Internal Revenue Service, Form 6765, Credit for Increasing Research Activities (Rev. December 2024), pages 1 to 4. https://www.irs.gov/pub/irs-pdf/f6765.pdf (accessed 11 October 2026).  Back
  18. Inland Revenue Authority of Singapore, Explanatory Notes to Form C-S for Year of Assessment (YA) 2026, section "Particulars of Person who Reviewed the Return". https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/explanatory-notes-to-ya-2026-form-c-s.pdf?sfvrsn=1d2386c1_20 (accessed 11 October 2026).   Back
  19. Inland Revenue Authority of Singapore, Research and Development (R&D) Claim Form (YA 2019 and onwards), Part 1 (note 1), Part 4 "Declaration" and Part 5, item 5O. https://www.iras.gov.sg/docs/default-source/uploadedfiles/pdf/rnd-claim-form-(ya-2019-n-after).pdf?sfvrsn=72929970_40 (accessed 11 October 2026).   Back
  20. Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 4, 7 and 21 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026).   Back
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  28. Internal Revenue Service, Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021), pages 1 to 6. https://www.irs.gov/pub/irs-pdf/p5.pdf (accessed 11 October 2026).   Back
  29. Internal Revenue Service, Research credit claims (Section 41) on amended returns frequently asked questions, introduction and questions 7 and 15 (page last reviewed or updated 1 October 2026). https://www.irs.gov/businesses/corporations/research-credit-claims-section-41-on-amended-returns-frequently-asked-questions (accessed 11 October 2026).  Back
  30. Inland Revenue Authority of Singapore, IRAS e-Tax Guide: Corporate Income Tax: Objection and Appeal Process (Fourth Edition, published 30 January 2026), paragraphs 2.1, 3.3, 6.1 and 6.2. https://www.iras.gov.sg/media/docs/default-source/e-tax/e-tax-guide_cit_objection-and-appeal-process.pdf?sfvrsn=83675467_11 (accessed 11 October 2026).   Back