Topical questions were those that were not repeated in each wave. These questions usually appeared in separate topical modules that followed the core questions. Topical modules were designed to gather specific information on a wide variety of subjects. They provided a broader picture of the types of individuals who were responding to the survey and give SIPP some flexibility in collecting data on emerging issues.

In some instances, the interview flowed more smoothly if topical questions were placed with core questions that relate to the same topic. For example, topical questions on asset balances were divided between items included in the core questionnaire and items included in a separate topical module. SIPP asked questions about ownership and an income amount in the core. However, questions relating to asset balances appear in the asset topical module.

Reference periods for items in topical modules vary widely, ranging from the respondent's status at the time of the interview to the respondent's experience over his or her entire life. When working with data from the SIPP topical modules, analysts should check question wording concepts carefully to ascertain the reference period. They should also check the universe for each question, because topical modules were not uniformly asked of all respondents. For example, only people 25 years of age or older were asked topical module questions about their retirement and pension accounts. Questions on shelter costs and energy usage were asked only of the reference person. In other modules, a screening question determined who was and was not asked the remainder of the module—in the case of the Work Schedule module, for example, only those who worked during the previous month answer the entire set of questions.