Background:
The strategy of raising taxes has reduced smoking prevalence in Brazil in the last few years. However, given the presence of illicit cigarette products in Brazil, smokers may have migrated to cheaper illicit cigarettes in order to save money, thus undermining efforts to further reduce smoking prevalence, mostly among underprivileged smokers. The aim of the present study was to estimate the proportions of illicit cigarette consumption in Brazil from 2012 to 2016.

Methods:
We used an approach based on legal sales provided by the Secretariat of Federal Revenues and self-reported consumption data from a phone survey conducted annually (VIGITEL) to estimate the changes over time in illegal cigarette use in Brazil, overall and by educational level. For that purpose, we also used available information on the proportion of illegal cigarette consumption from a nationwide household survey conducted in 2013 to calculate a constant proportion of under-reporting from VIGITEL in relation to total sales in Brazil.

Results:
There was an increase in the estimated proportion of illicit cigarette use from 2012 to 2013 (+12.9%), then a decrease from 2013 to 2014 (-10.8%), and then a sustained trend of increase from 2014 to 2016 (+26.7%, from 2014 to 2015; +17.3%, from 2015 to 2016).The same pattern was observed for both high and low educational level smokers. For each year, the latter had higher baseline proportions of illegal cigarette use.

Conclusions:
Novel and feasible approaches to estimate the changes over time in illegal market are important to help in the effective implementation of tobacco excise tax policy.