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The International Journal of the Royal Society of Thailand
Volume XII, 2020

of expenses are combined in the research data provided by RD. This means the
sample cannot be used to examine the impact of rules applying to different
types of income grouped together in this category.

Possible improvements

1. Remove taxpayer location (province) from sample records to improve
top-end coverage. Although data by province are very useful for research it is
sufficient and more reliable to present the information in the form of summary
statistics derived from the full database that accompany the sample.

2. Investigate and clarify discrepancies between averages for the full
dataset and averages for the sample in cases where these are substantial
(e.g. differences of more than Baht 10 billion exceeding 5% of the national figure).

3. Provide breakdown by income type for income before and after
expenses reported under 40(8).

4. Analyse the excess of tax receipts over assessments recorded on
PND90 and PND91 forms (e.g. tax credits not included on forms or tax credits
in excess of tax liability that are not refunded).

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Francis Cripps and Pasuk Phongpaichit

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