This paper investigates whether evidence of linguistic accommodation can be found in the writing of first-generation migrants who have joined settler communities in areas where that language had not been spoken long before their arrival, i.e. so-called tabula rasa contexts (Trudgill 2004). Schneider’s (2003, 2014) dynamic model for the evolution of World Englishes and Trudgill’s (2004) new dialect formation predict that in these contexts, dialect mixing takes place as a result of linguistic accommodation in face-to-face interaction. This paper investigates whether traces of this accommodation can also be found in writing and uses the context of Irish migration to Australia in the nineteenth century as a case study. The results are based on a quantitative analysis of a corpus of emigrant letters produced by Irish writers living in Ireland, Irish living in Australia, and English living in Australia, totalling c. 200,000 orthographic units. The analysis consists of a comparison of preterite/perfect alternation in the three subgroups, as well as three case studies of individual authors. The results indicate that the group of Irish Australians have distribution rates for the perfect closer to their English Australian peers than to those who remained in Ireland. An in-depth analysis of individual Irish Australians suggests that not all of them show this higher distribution rate, but at least some of them do, and one even showed an increase in perfect use the longer he lived in Australia.