Abstract: Background: Men have a greater risk of colorectal cancer (CRC) than women, but population screening currently starts at the same age for both sexes. Aim: This analysis investigates whether, in a resource‐constrained setting, it would be more effective and cost‐effective for men and women to start screening for CRC at different ages. Methods and results: An economic modeling analysis was carried out using the Microsimulation Model in Cancer of the Bowel to compare sex‐stratification against screening everyone from the same age, taking an English National Health Service perspective. Screening men from age 56 and women from age 60, rather than screening everyone from age 58 using a Fecal Immunochemical Test (FIT) threshold of 120 μg/g is expected to produce an additional 0.0004 QALYs for a cost of £0.55 per person at model start (Incremental Cost‐effectiveness Ratio = £1392), and to reduce CRC cases and mortality by 25 and 19 per 100 000 people respectively, while using a similar amount of screening resources. Probabilistic sensitivity analysis indicates a 61% probability that sex‐stratification is more cost‐effective than screening everyone at age 58. Similar benefits of sex‐stratification are found at other FIT thresholds, but become negligible if mean screening start age is reduced to 50. Conclusion: Where resources are constrained and it is not feasible to screen everyone from the age of 50, starting screening earlier in men than women is likely to be more cost‐effective and gain more health benefits overall than strategies where men and women start screening at the same age.